Ice Diving

If you thought diving was a fascinating sport, just wait until you discover how adventure sports always push boundaries—giving you the chance to experience scuba diving in an environment unlike anything you’d imagine... beneath the ice itself.

Attractions and sensations of an extreme activity

In late autumn, as temperatures drop, mountain peaks begin to blanket in white snow, and their ibones—the name given to high-mountain lakes— start their annual cycle of freezing their crystal-clear waters. This is the time to prepare your diving gear for one of the most spectacular experiences winter has to offer: a dive beneath the heart of the ibones.

Ice diving is an extreme sport in a highly hostile environment, requiring significant technical and physical preparation. But as a reward, this activity delivers a unique experience that will flood your body with adrenaline.

A world of visual contrasts (brightness at the virtual ice ceiling and darkness below), dormant wildlife (amphibians, fish, crustaceans, flora, etc.), and, ultimately, a wealth of new sensations await in this type of dive. Numerous factors place it at the limit of human capability (hypothermia, altitude, physical exertion, altitude diving-related dysbaric accidents...), but these risks are easily minimised with knowledge, proper planning, and the right equipment.

Once you’re ready to plunge into the icy waters of high-altitude lakes beneath an ice layer ranging from 20 centimetres to a metre and a half thick (depending on external and internal temperatures, altitude, etc.), it’s crucial to meticulously organise the expedition, following steps that cannot be skipped if you want to preserve an unforgettable memory of this dive.

Advanced planning

Prior research

It’s essential to know in advance—with absolute certainty—the weather conditions in the area. To do this, check weather reports and local news for potential changes on the day of your planned ice dive. A solid understanding of high-mountain weather is key to the success of your adventure. Cancel the dive if there’s a risk of avalanches, extremely low temperatures, excessively thick ice, potential storms, heavy snowfall, etc.

We’ll also need to know the exact altitude and atmospheric pressure to calculate decompression if necessary. For this, we’ll use dive tables and computers.

Guided diving

One critical point: ice diving should only be done accompanied by certified or recognised instructors specialising in this activity, as they’ll ensure safety and reliability during the dive. Ice instructors are trained to analyse the ice layer beneath the lake, which is vital for guiding us safely underwater and handling any incidents that could escalate into accidents. It’s strongly discouraged to attempt ice diving alone without expert assistance.

This involves knowing in advance and with full certainty the weather conditions in the area. Check weather reports and local news for potential changes on the day of your ice dive. A good understanding of high-mountain weather is essential for a successful adventure.

Procedures and "on-site" preparations before the dive

On-site study of the lake’s ice layer

The thickness of the lake’s ice layer is analysed to determine its strength and load-bearing capacity. With thin ice, around 5 centimetres, it’s advised to enter from the shores (less prone to freezing). Thicknesses nearing 10 centimetres require close attention to external temperatures (if below zero, the ice will hold well; if above, the surface layer may weaken). Thicknesses around 20 centimetres are ideal for diving and setting up equipment near the entry hole. It’s advisable to secure with a line the person cutting the hole.

Setting up a safety line

Always tie a line near the shore to a tree, rock, etc. If impossible, fix it with ice screws away from the dive site. This line aids approach to the entry hole and helps divers return to shore, as well as serving as an anchor point for a safety reel.

Creating the entry and exit hole

Make it triangular or rectangular, but never square or round. The first two shapes ease entry and exit, as divers can brace better against the edges. Depending on thickness, use a handsaw (for thin ice) or a power saw (for thicker ice).

Team formation

It’s best to dive in teams of three divers maximum, plus one surface diver holding a reel line attached to the submerged divers. Another standby team should be ready to assist if the surface diver signals issues, as they’re the only link via line signals to the submerged divers.

Establishing a safety perimeter

Mark a 15-metre radius from the hole’s centre. This safety distance prevents excessive weight on the ice, reducing fracture risks. All divers on the ice must wear full gear in case of ice breakage.

Equipment and gear

Twin-cylinder with dual valves and two regulators

With an isolated or sealed high-pressure chamber. Diaphragm-balanced regulators excel here. Some models use special grease with a freezing point below water’s, preventing mechanism freeze-ups. These regulators nearly eliminate internal freezing from ambient air or water temperatures, avoiding free-flow failures. We recommend not breathing through the regulator above water to prevent ice formation.

Suits and gloves

Suits must be completely dry, as temperatures typically range between 1°C and 3°C, while outside they’re often below freezing. Critical for preventing hypothermia. Similarly, gloves must be sturdy yet allow dexterity and blood circulation in hands and fingers.

Guideline and reel

As mentioned, held by the surface diver, but each diver connects via carabiner. The entry hole is the only exit, so tethering is mandatory. Each diver carries a 50-metre reel, linked to the main line held by the instructor-guide.

Dive computers and underwater lights

Remember: this is altitude diving. Residual nitrogen parameters (if unacclimatised—e.g., arriving days early) require treating this as a repetitive dive, necessitating dive computers.

Underwater lights are placed under the ice, especially if snow cover reduces visibility, making artificial light essential. Chemical lights can also mark divers’ positions, as in night dives.

Other equipment mirrors standard open-water diving gear.

The dive

Never exceed 30 minutes underwater. Always monitor depth and ascent rate (~9 metres per minute). A safety stop at three metres (adjusted for altitude) is advised. Avoid significant altitude gains post-dive.