Anybody have comments about the scuba divers down at 581' and surfacing quickly?
They would be breathing hypoxic trimix as a bottom gas and use varying percentages in their stages used during descent and ascent. Which from nearly 600' would take a considerable amount of deco.
They would have multiple safety divers in the water at different depths. Each would be capable of a fairly quick ascent to the next shallower safety diver to hand off the free diver.