He eases up to a small boat anchored near the pilings that is flying a diver-below flag, and notes the name and number of the boat, to make sure that it is official.
The mussels were discovered in December by two divers from Bateaux Below, a nonprofit group whose members survey the lake's dozens of 18th-century shipwrecks.
Narcosis is potentially one of the most dangerous conditions to affect the scuba diver below about 30 m. Except for occasional amnesia of events at depth, the effects of narcosis are entirely removed on ascent and therefore pose no problem in themselves, even for repeated, chronic or acute exposure.
I'd recommend the underwater sculpture park by Jason deCaires Taylor, which snorkellers can see from above, divers from below.
Above the scuba divers, and below the snorkellers, a large shark, more than two metres long, was slowly circling the group.
Molchanova was diving in an area known for strong currents and heavy boat traffic, where the water temperature can dip sharply once divers get below the surface – something that can affect even the most experienced of divers.
If, like me, you are just a proletarian snorkeler, even swimming through the clouds of bubbles exhaled by the divers far below you is still part of the almost mystical experience.
After all, seeing cool fish and colourful coral is the main reason divers descend below the surface.
It's this very plasticity - and the physical training that produces it - that allows climbers to summit the world's highest peaks, divers to plunge deep below the ocean's surface, ultramarathoners to run a hundred miles, weightlifters to bench press a thousand pounds.
