Diving in Frozen Lakes
These lakes are usually located in high mountain areas where, at certain times of the year, their surface remains frozen. Thus, ice diving at altitudes above 3,000 metres falls into the category of special high-altitude dives. With water temperatures close to 0°C, safety measures must be maximised, and equipment must be adapted to these extreme conditions.
The allure lies not only in observing the scarce (and in some cases dormant) aquatic life but also in witnessing the sunlight filtering through the ice.
Ice diving carries significant risks, so safety measures must be rigorously followed to minimise hazards. This type of diving is reserved for those with highly specialised techniques for such immersions and proficiency in using specialised equipment designed for extreme conditions.
Similar to cave diving, diving under ice involves navigating beneath a solid ceiling, making a direct ascent to the surface impossible.
For pre-dive operations conducted on the frozen surface, divers must wear an insulated dry suit (as a precaution in case the ice layer breaks). Divers should also be tethered via a line to a harness, maintaining a distance of approximately 10 metres between the safety team (stationed in the risk-free zone) and those performing the ice-cutting work.
A suitable area with ice no thinner than 20 cm (to support the divers' and equipment's weight) must be selected. The entry hole should be cut using a mechanical saw in a triangular shape with closed vertices to facilitate easy entry and exit for divers.
Specialised Equipment
Once the entry hole is prepared, divers must equip themselves with:
- A variable-volume dry suit, preferably with a fleece liner or similar thermal clothing underneath, along with gloves and a hood to protect ears and hands upon exiting the water.
- A double regulator equipped with cold-water protection. To prevent regulator freezing on the surface, it should not be used outside the water (due to cooling caused by air expansion in the regulator's first stage, dropping from ~200 to 10 atm).
- A dive computer—or alternatively, account for the lake's altitude if using decompression tables to adjust depth corrections and decompression stops (though these are strongly discouraged in such dives).
Divers must remain connected to the surface via a guideline, and to each other (enabling communication through line signals). Remember: ice cannot be broken underwater with a knife, so the guideline is crucial for locating the exit.
On the surface, a teammate feeds the guideline to the divers, while a fully equipped pair remains on standby as emergency support.
To mitigate hypothermia risks, high-energy foods (chocolate, energy bars, etc.) and multiple thermoses with hot drinks are essential.
