When Canadian Sharkwater director Rob Stewart died in a scuba diving accident off of the Florida Keys in January 2017, he was diving with a piece of diving equipment commonly used by military and technical divers — a rebreather.  

With traditional scuba tanks, the diver breathes from a compressed air tank that he/she carries until all the air is drained. But rebreathers are devices that allow a diver to keep reusing the air they’ve already inhaled.

This means that divers who are travelling to very deep locations for a long time rarely run out of air. Divers are also able to eliminate long rest stops to let nitrogen bubbles leave their bodies as they surface, otherwise necessary to avoid getting depression sickness or ‘the bends’ which can be deadly. 

Rebreathers don’t let bubbles out into the water, which can be a big advantage for divers who wish to observe wildlife at close range.

Rebreather instructor Peter Sotis explains how the technology works in the video above.

To learn more about Stewart’s final dive, watch The Third Dive.