Version 2 – Oct 2007

Guidance on Free Flow Regulators in Cold Water
Fresh water sites can often be close to freezing, even outside the obvious winter period. This often poses the threat of a free flow. Incidents resulting from free flows cannot be completely avoided but they can be reduced if a few basic guidelines and procedures are followed.

What can cause a free flow to occur?
When air flowing from a diving cylinder is subjected to dramatic reductions in pressure (a change from 230 bar to around 10 bar) by the regulator first stage, it loses a lot of heat. If the surrounding water temperature is cold (around 5oC or less) this will reduce the temperature still further. The very cold air caused by such temperature drops in each stage of the regulator can cause any water droplets within the mechanism to form ice crystals, which in turn can cause a free-flow. Modern down-stream valves will freeze open rather than shut, but, if they freeze, a free-flow will always be the result. Divers are trained to manage free flow situations in basic dive training.

Diving in conditions that are cold can increase the likelihood of a regulator free flow. Being prepared and anticipating this event will increase your chances of dealing with the incident in a safe and controlled manner.

  • Use a cold water environmentally sealed regulator. The most important consideration will be to have the regulator serviced regularly specifically for cold water. Many of the top regulators meet the European standard (EN250) for cold water.
  • Familiarise yourself with the adjustments you may want to make at the dive site and follow proper cold water diving principles detailed below.
  • Try to ensure that your cylinder is kept free of moisture and has been filled with air containing as little moisture as possible.
  • Keep your cylinder out of the cold until you are ready to use it. (Don’t leave it in your car overnight.)
  • Blow away any entrapped water (or ice) that may be on your cylinder valve or regulator orifices, with a little air from your cylinder.
  • Take check-out breaths submerged in shallow water immediately before diving rather than in the air.
  • Avoid the cooling effect of fast air flows caused by using the purge button or breathing heavily, or filling delayed SMBs or lifting bags.
  • Do not permit any water to enter the 2nd stage before or during the dive.
  • Consider restricting yourself to no-stop diving, and to a depth from which you are certain you are able to make a free ascent.


  • Practice free flow regulator drills and the use of redundant air supplies for such instances. The use of a redundant air supply such as a pony bottle and regulator, or an additional first and second stage mounted onto a Y-valve should provide reliable source of additional breathing gas when a free flow occurs.
  • Ensure all alternate air source systems are in plain view and conspicuously marked allowing access at all times.
  • Discuss the in water procedures and techniques that should be used when dealing with this situation and clearly agree with your buddy on the action to take in each case.

In-water response to a free flowing regulator
When a regulator suddenly goes into free-flow it can be very startling as there is a sudden roar of bubbles and visibility is reduced. The main strategy is to:

  • Remain calm Stop – Think – Act
  • If you are confident in breathing from the free flowing regulator do so, but check and prepare alternate sources just in case.
  • If an alternate air supply is preferred and available switch to it. An alternate air source might constitute an ‘octopus’ regulator or a fully redundant air supply, such as a pony cylinder and regulator.
  • Abort the dive and head for the surface in a controlled manner with your dive buddy
  • Once on the surface, establish positive buoyancy as soon as possible

Breathing from a Free Flow
Modern high-flow regulators which freeze open can produce extremely powerful free flows. Even very experienced divers may find it difficult to breathe effectively from a free flowing regulator in these circumstances. Practice breathing from a free flow regulator as indicated by your training organisation. Whichever method is adopted ensure that you do not seal your lips around the mouthpiece. You may use your tongue as a splash guard to prevent choking on water.

This technique takes practice to perfect and to feel comfortable with it, so take every opportunity to simulate it in safe conditions. Moderately powerful free flows can be simulated by pressing the purge button.

Do not assume that you or your dive buddy will always be able to breathe from a free flowing regulator – be prepared to switch to a normally operating source of breathing gas, or to offer your buddy an alternate air source, if required. Bear in mind the possibility of your alternate air source also free flowing in very cold water. The use of pony cylinders and regulators offer divers a fully redundant air source in these circumstances.

Using an alternate air source supplied by another diver
The most common alternate air source is the alternate second stage or “octopus,” normally secured in plain view in the triangular area between the chin and the corners of the rib cages. Whether the donor breathes from the primary or the secondary regulator depends upon the regulator configuration and other factors. Generally, it is desirable for the donor to retain the primary regulator and provide the alternate, but alternate inflator regulators and other configurations (such as redundant air supplies) have require the donor giving up the primary to the receiver and then switching to the alternate.

The important point is that buddies know how each other’s systems work. The receiver secures the alternate after sufficient time to adjust. The team establishes contact and then ascends face-to-face or side-by-side as appropriate for the configuration, with the face-to-face, grasping right fore arms the most common. During the ascent, divers control their buoyancy to maintain a normal ascent rate.

By implementing some of the suggestions above and by discussing possible reactions to a free flowing regulator with your buddy, you will reduce the likelihood of such an event occurring and improve your responses to the situation should it arise.

Stoney Cove is open for diving 362 days a year.

We are open for diving
Monday – Friday 8:30 and 16:00  
Saturday & Sunday 08.30-15.00 

Monday to Friday 08.30-16.00
Saturday & Sunday 08.30-16.00

Diving at Stoney Cove costs £27 for each diving session for visitors, and £20 for Diverlog card holders. 

Save £7 every time you dive at Stoney by joining our Diverlog registration scheme.

Want to go diving, but you haven’t bought kit yet, or maybe you’ve forgotten to pack your fins? No problem at Stoney Cove, why not hire it.
We hold an extensive range of equipment for hire all booking are via telephone on 01455 273089.


Suit Hire
Dry suits (excluding undersuit) are available for hire to visitors with a dry suit qualification, please provide your own undersuit.

FULL SET PACKAGE – with Semi-Dry £57.00
FULL SET PACKAGE – with Drysuit – £72.00
SEMI-DRY SUIT – £15.00
REGULATOR– Complete with octopus & gauges £12.00
CYLINDER – 12 Ltr & 10 Ltr available, complete with fill £12.00
BCD – Stab Jacket £12.00
FINS £4.00
BOOTS £3.00
HOODS £2.00
MASKS £3.00
DRY SUIT £30.00

For weekend use, hire equipment can be booked by telephone, on 01455 273089

When booking suits for weekend use please have to hand, chest, height and waist measurements.

The Benefits to you
Stoney Cove maintains an approved system of safety procedures, they are in place to help both our staff and our customers to enjoy diving at Stoney Cove.
Registering divers helps provide information to the rescue team if needed in any incident.

Subscribing to the Diverlog scheme means that you only have to supply this information once. It’s also designed to speed up your entry into Stoney Cove when you visit.
Dive at Stoney Cove at a discounted entry fee of £20 per session, a saving of £7

Always remember to bring QR Code ready for scanning on arrival.

A Diverlog registration costs £40 valid for two years or £30 for one year and is available online.

The Rules and Regulations

  • All visiting divers must have a ticket ready for scanning on arrival.
  • Always follow the Stoney Cove recommendations for responsible diving and safe diving practices of your diving associations e.g.: BSAC, PADI, SAA, SSI etc.
  • Do not dive solo,and if you become separated from your buddy or group, ascend and rejoin at the surface.
  • You must meet the minimum age requirement of your training association and be no younger than 12 years old.
  • Junior participants must be closely supervised by adults.
  • All diving schools, instructors and other divers, who use Stoney Cove in an ‘at work’ situation, i.e. receive payment or some other form of favour or reward must operate within the requirements of the Diving at Work Regulations 1997 and notify us of any diving project conducted at Stoney Cove.
  • The use of images still or moving of any part of Stoney Cove for commercial purposes requires specific permission.
  • Wear a buoyancy aid at all times.
  • Plan your dives with consideration to our regulations, recommendations and information we provide.
  • Read our notices, if unsure ask us, assess the risks associated with Stoney Cove and its features, if in doubt don’t dive!
  • Diver propulsion vehicles can only be used with extreme caution, and never in poor visibilty.
  • Do not dive outside the displayed opening times.
  • When using a rebreather, use either a Surface Marker Buoy throughout your dive or use a delayed SMB to mark your ascent.
  • Used Sodalime from rebreathers must be a disposed of away from Stoney Cove.
  • Do not run, shout, wave of blow whistles unless there is an emergency.
  • Do not damage or remove pieces from the objects of interest in the water, or cause any harm to the wildlife above or below the water.
  • Keep the volume of car radios down.
  • Do not leave children unsupervised.
  • All dogs must be kept on a lead – please clean up after them.
  • Do not use any naked flame device, including BBQ,s.
  • Please drive vehicles slowly with care, do not obstruct any roadway or access and have respect for each other and our neighbours.
  • The decanting of oxygen or the use of portable compressors is not permitted anywhere on the site.
  • Please follow all directions given by Stoney Cove staff.
  • Stick to the rules.
  • We reserve the right to refuse entry, suspend or cancel the Diverlog registration of any diver or contractor who contravenes the Stoney Cove regulations.

We try to make Stoney Cove as safe as possible, but there are a number of hazards that you may encounter and should be prepared to avoid. These may seem obvious, but they are highlighted here to help you enjoy a safe dive.

Slip and trip hazards
Walking in heavy, cumbersome dive gear is hazardous and the approaches to the water entry points are slopes or steps, which can become slippery when wet. The slipway should be avoided, as this slope is always wet and slippery.

Breathing water may result in drowning.

Falling rocks
Rocks may fall from the cliffs surrounding Stoney Cove, both above and below the water, so keep away from the base of any cliff.

A number of areas and some of the underwater features have entanglement hazards. Do keep a safe distance from the features and the lake bed.

Some of the features have accessible interiors. If you venture inside the feature, you may become trapped.

Some areas of the lake bed are covered in a heavy deposit of silt. Disturbing the silt will impair your visibility and you and others may become lost or disorientated. To avoid this, swim at least a metre above the silted lake bed.

WARNING: Scuba diving can be dangerous, incidents can occour, sometimes with fatal consequences. All divers have the responsibility for their own safety. Instructors, dive guides and diving buddies have a duty of care for those who are diving with them. divers are reminded that they have the responsibility for the first actions to effect a successful rescue.

Important Notice
Scuba diving and Open Water Swimming can be dangerous and incidents can occur, sometimes with fatal consequences. All divers and swimmers have a responsibility for their own safety. Swimmers, Instructors, dive guides and diving buddies have a duty of care for those who are participating with them. All participants are reminded that they have the responsibility for first actions to effect a successful rescue.
Stoney Cove staff will respond at once to provide first aid in any emergency, either in or out of the water.

In the event of any incident, alert the shop staff immediately.

What to do if your buddy gets into difficulty

Wherever possible, help them to the surface by releasing their weight belt.

Raise the alarm at once by blowing a whistle, shouting and waving.

If you see someone in trouble, raise the alarm immediately. While someone else alerts staff in the shop, stay where you are, monitoring the position of those in the water.

Stoney Cove’s Rescue Plan

  • During diving hours, the rescue boat is stationed at the rescue jetty, ready for immediate use. The boat will be launched to assist any person in distress. The boat contains a shot line and reel with line ready to be used in a search for a lost diver. Three members of staff will board the boat: the boat handler, a lead first aider/oxygen provider and an observer/first aider.
  • Oxygen resuscitation equipment is kept in the rescue boat and at strategic points around Stoney Cove, ready for staff to use.
  • In the event of an incident, other staff will immediately move to their designated rescue positions, for example, waiting on the rescue jetty with additional oxygen, defibrillator and a stretcher. They are ready to call the emergency services whenever necessary.
  • Substantial oxygen supplies are kept on site at all times for use in the resuscitation sets.
  • If a diver is missing in distress, Stoney Cove staff will organise and manage a search. They may ask for volunteer divers, who will be asked about their level of competence and their ability to take part in the search without endangering themselves. If a diver is ill, staff will administer first aid until the emergency services arrive.
  • Any diver with decompression sickness will be transferred to the nearest available recompression chamber, usually by air ambulance.
  • All accidents at Stoney Cove are recorded and full reports given to the appropriate associations and authorities e.g. BSAC, PADI, HSE.

We advise you make the most of your day with us and use the interactive map of the lake to help you navigate it’s many attractions and features. This maps features is best viewed on a tablet or desktop PC. The guide below outlines some of the attractions beneath the surface of the lake.

See The Under Water Map

Welcome to Stoney Coves pre-book car parking

As everybody knows getting to Stoney Cove at some ridiculously early hour just to get a place on the inside car park is a real pain, so how about reserving your place and arriving at your leisure.

If you are Diverlog registered and would like to pre-book a space on the inside car park this can be done from March 2022 via the ticket site when booking your ticket
(weekends only) . The number of bookable spaces is limited to 20, with a £10 none-refundable fee applies for the parking. 

Please Note

These spaces are not available to dive schools, large vehicles and groups of divers in excess of 4 persons and are limited to one per booking. If these conditions are not met, entry may be refused.

Diving in the dark at night can be an amazing experience especially when the visibility is very good. If you never tried it watch the fantastic diving film “The Abyss” this will give you some idea of what to expect. To get the most out of the dive try a brief period with your torch turned off, now you will see the features illuminated by you buddies torch and because you are not behind the light source you won’t see the reflection from the suspended particles in the water. The effect this has on the large features like the Stanegarth is magical. To swim alongside the wreck and see light streaming out of her portholes from the torches of the divers exploring her cavernous engine room is surreal.

Stoney Cove is open for night diving the 1st and 3rd Wednesday of every month between 18:00 and 21:00

Stoney Cove recommend divers have at least 10 logged dives before under taking there first night dive and must dive with a torch and carry a personnel location device, light stick or strobe

Following an increase in interest from customers we have decided to re-open Stoney Cove to snorkellers.

Snorkelling is great fun, easy to learn and an ideal way to build up confidence in the water. It is accessible to anyone and is also a great introduction to underwater sports.

Here at Stoney Cove we have ideal, sheltered conditions for snorkelling. The 7m shelf has many exhibits that are visable most of the year including 400 year old Elizabethan shipwreck.

Stoney Cove’s 13 acre, spring fed fresh water lake offers a 1000 metre perimeter course in Leicestershires cleanest water. Our shore facilities include hard surfaced car parks, showers, changing rooms and the all-important bar and restaurant.

Stoney Coves package is hard to beat and is fully supported with a rescue boat on constant standby and qualified first aiders.

Entry fee is as standard diving price (see above)
Snorkellers must be in pairs or groups. No solo.
Life jackets must be worn
Minimum age 12 years
Adult supervision required for under 16s

Please click this link to read the Stoney Cove Guide Book in full.

7 Metres

Entry Level Areas

22 Metres

Intermediate Areas

36 Metres

Expert Areas

There’s an underwater world waiting to be discovered in Stoney Cove. The terraced dive areas are graded to reflect ability, with depths of 7 metres (entry level), 22 metres (intermediate) and 36 metres (expert). Don’t be tempted to dive too deep too soon. There’s plenty to see at all depths. It’s vitally important to remember that the climate has a dramatic effect on diving conditions throughout the year. Before taking the plunge, consider the following useful information… and plan your dive.

Maximum depth: 7 metres
Who: All divers (including trainee divers accompanied by an instructor or other suitably qualified diver Where: Adjacent to the car park, on the north side of Stoney Cove. Getting there: Accessible directly from the bus stop, Eddy’s Quay. What’s there: This 7-metre deep shelf provides excellent shallow-water diving in the warmest thermocline with bright light conditions. Look out for the following: (Numbers relate to the appropriated picture) (numbers in brackets refer to the map)

1. Viscount aircraft cockpit Map ref 1
Interested in wreck exploration? This is the perfect place to start. The cockpit rests on the top of the roadway that leads down to deeper water. Submerged in Stoney Cove as part of a joint rescue services training exercise, it is now crewed by some of the larger fish – pike and perch can often be seen keeping watch on the flight deck.

2. The Nautilus Map ref 2
Jules Verne’s vision of an underwater realm is now a reality. The Nautilus – Captain Nemo’s sub – rests patiently on the 7-metre shelf. Ten metres in length, with a menacing bow and a massive propeller at the stern, this unique piece of diver art – entirely constructed of steel – is well worth a dive.

3. Archways beneath the pub Map ref 3
The archway and windows beneath the pub were originally built by Italian POWs, as part of the quarry stone- crushing plant. On a sunny day, light streams into the dark interior. Freshwater crayfish are often found here. But please don’t touch – handling may kill them.

4. The Gresham Ship Map ref 26
The ship was an armed Elizabethan merchantman that sank to the bottom of the River Thames over 400 years ago. Its new home is Stoney Cove, where it has now become part of a unique underwater museum for visiting divers as well as a practical survey site for students of underwater archaeology.

Maximum depth: 22 metres
Who: Advanced trainees accompanied by instructors; newly qualified divers with experienced dive leaders; advanced divers. Where: There are two areas. The first and larger area is next to the 7-metre shelf (south of the pub), directly down the cliff face, while the second is at the western end – often called the Bowl or Top Basin. Getting there: The first area is accessible directly from the bus stop or Eddy’s Quay. To reach the second area, go to the right from the bus stop. What’s there: More than 60% of Stoney Cove is about 22 metres deep. These areas provide good intermediate-level diving with varied terrain and spectacular cliffs, with light levels ranging from good to dark. Here are a few of the many features you may see:

4. The Wessex Map ref 4
The wreck of a Wessex helicopter sits close to the northern cliff face. Flown for just 650 hours, it was in immaculate condition before the rotor blades were detached and it was plunged in Stoney Cove. Souvenir hunters have plundered the helicopter, but it remains an excellent wreck to visit, particularly as an introduction to deeper diving.

5. The Bus Map ref 5
The bus sits in a flat, silty area, 25 metres away from the edge of the cliff that drops down to the 36-metre area. Its large open window and skylights make the bus an excellent swim-through. (Look out for Rodney and Rodette!) Swim above the silt to prevent stirring it up and reducing visibility… Finding the bus is a navigational challenge. We’ve even been accused of moving it.

6. The Monster Map ref unknown
Its exact whereabouts are unknown, but Stoney Cove’s resident beast, Nessie, can be easily identified by its green skin, yellow spots and Mona Lisa grin.

7. The Galleon Map ref 7
The remains of the Galleon lay in 5 metres of water on a ledge in the far south-east corner of Stoney Cove. This reproduction of an ancient wreck, constructed by the Midland Underwater Archaeological Group from 17th-century timbers was convincing, but time has worn it down. Look out for the canon.

8. Aircraft Wreck and Wooden Boat Map ref 8 & 14
These are superb wreck dives in the area known as The Bowl – a 20-metre-deep shelf in the south-west corner of Stoney Cove. The first sign you’ll see of the small Partenavia aircraft (8) is its tail, which touches the cliff face at a depth of 18 metres. Nearby, the wreck of a wooden boat (14) rests on a steep slope 20 metres south.

15. Stanegarth Map ref 15
The Stanegarth arrived at Stoney Cove in June 2000. It’s a steam-powered tug, built in 1910, which makes it older than the Titanic. Lying roughly east-west, with her anchor and chains played out towards the shore and perfectly upright, Stanegarth is one of Stoney Cove’s most popular diving features and the UK’s most dived wreck. To dive her is a joy, with access to the chart room, wheelhouse, engine room and aft cabin. A buoy attached towards her stern marks her position.

16. FV432 APC Tracked Armoured Personnel Carrier Map ref 16
Designed to carry a driver and ten infantrymen, the APC, or the Tank as it is now known, was built in 1964 and was based at Ludgershall. It was withdrawn from active service in 1971 and then went on to be used in vehicle trials. Its vital statistics are 5.11m x 2.82m x 1.88m, it weighs 8 tons, was equipped with a Rolls Royce engine and was once used for transportation, river crossings and winching tasks.

17. Defiant Map ref 24
The tugboat Defiant is a pretty Dutch tug with an interesting war history. Rumour has it that she was the escape vessel for two men escaping to England during World War Two. At 14m (46ft) long and 20 tons she is smaller than the Stanegarth, but she is superb. Discovered ashore at a farm in Warkworth on the north-east coast, she was brought to Stoney Cove in 2009 and sank along with our usual fanfare on 17 September. It is possible to swim into the wheelhouse and engine room, but be aware that the space is very confined.

18. MV Belinda Map ref 25
Belinda is a small steel-hulled trawler that was abandoned after a round-the-world trip fizzled out. She once earned her living netting fish in the North Sea. Belinda has a sturdy wheelhouse and still carries her net winches and trawl gear. She slid beneath calm waters of Stoney Cove on 4 June 2010.

Max depth: 36 metres
Who: Very experienced and expert divers. Where: Directly in front of the Dive Centre and Underwaterworld Megastore. Getting there: Follow the road down from the bus stop or surface swim to the right and descend the Hydrobox buoy line. What’s there: The sump or bottom of Stoney Cove provides an ideal training or practice environment for advanced and expert divers. Here, the water temperature is about 5oC and the light levels can vary from good to zero. The area is quite large and has a fairly flat bottom surrounded by spectacular rock piles and cliffs. But beware the deep silt, which can reduce visibility to zero. The major attraction in this area is:

9. The deep Hydrobox Map ref 9
An orange buoy marks a line leading down to the deep Hydrobox – a large metal structure some 5 metres tall. There’s a round entrance on top of the box, designed to provide a dry working environment for welding and other tasks. If the lid is closed, the box can be filled with air, allowing divers to enter through the gap between the floor and the sides. Look out for the massive ballast weights that keep the box firmly on the bottom of Stoney Cove.

27. The SHIERS BELL Map ref 27
During a very snowy week in February in 2017, our friends from 21 Engineer Dive Team gave us a helping hand and lifted the Bell to the surface ready for its move. During a blizzard, the Bell was carefully towed across the lake and lowered into position, 25 metres west of the Hydrobox – the final move in a massive project. The Shiers Bell now stands proudly at the bottom of Stoney Cove as a testament to the epic work carried out by divers during construction of the Thames Barrier during the 1970s. Our thanks go to everyone that contributed to this project and especially to Tim Prince. A leading member of the oldest established scuba diving club in the UK – The Birmingham Underwater Exploration Club – Tim introduced us to The Shiers Diving Bell in the first place. Cheers!

Please Dive Safely
Respect The Rules