Brine pools are highly saline underwater lakes known to be toxic to most sea life, and yet they hold the promise of biological secrets that could lead to medical breakthroughs. Formed when ancient salt deposits leach into the ocean, brine pools are so dense that it's difficult to penetrate their surface. Their high salinity, often combined with heavy concentrations of hydrogen sulfide and methane gases, makes them lethal to most creatures that try.

On one of our dives, we captured extraordinary footage of an eel venturing into the murky depths of a brine pool in search of food. The toxic shock was so great, the eel immediately went into spasm, recovering only after drifting out of the brine pool’s deadly embrace. But what’s most intriguing about these brine pools is that smaller organisms have actually adapted to live within them—some able to convert methane into energy. Scientists believe that studying this unique microbiology could someday lead to breakthroughs in biotechnology that could cure cancer and other diseases.

Our crews witnessed one more amazing scene on their dive to the brine pools: giant methane bubbles, the size of basketballs, erupting from the ocean floor. The vast, still depths were suddenly transformed into an exploding sea bed, an incredibly dramatic event—recorded by our cameras for the first time ever—that has given science yet another intriguing subject for study.