Scripps marine biologist shares findings about the deepest spot on Earth

By Claire Discenza

“The most exciting dive was the very first one,” said Doug Bartlett, marine biologist at Scripps Institution of Oceanography. Bartlett was one of the researchers who accompanied film director and producer James Cameron on his famous journey to the depths of the Mariana Trench in the spring of 2012.

Bartlett presented “Exploring Beyond the Abyss: The DeepSea Challenge Expedition” as December’s installment of the Jeffrey B. Graham Perspectives on Ocean Science lecture series hosted by the Birch Aquarium. In his talk, Bartlett gave the audience a play-by-play of Cameron’s adventures.

“It was just magical. It was like 2001 Space Odyssey,” said Bartlett as he played an eerie video of Cameron drifting down through a haze of sediment toward the floor of the Mariana Trench. At 8.2 kilometers below the surface, it was the deepest descent of a manned submersible at the time.

The researchers later beat their own record on March 26 when they sent Cameron down to the bottom of the Challenger Deep, the base of the Trench.

“There is still some issue as to exactly how deep [the Challenger Deep] is,” said Bartlett. “But it is in the ballpark of 36,000 feet or more. That’s deeper than commercial airlines fly, than Mount Everest or any mountain is high.”

Cameron traveled the nearly seven vertical miles inside of what Bartlett jokingly referred to as “12 tons of fun” — a one-man torpedo submarine so small as to require the pilot to sit all 9 to 12 hours of the trip cross-legged. The sub provided other discomforts as well: the internal temperature occasionally rose to above 100-degrees Fahrenheit.

Yet the strenuous voyage payed off, as Cameron and the submersible were able to film, photograph and collect never-before-seen marine samples — both biological and mineralogical.

At the most extreme depths, the team observed examples of “gigantism,” collecting shrimp-like crustaceans called amphipods that were over twice the size of their shallow-water counterparts. The researchers also found some of the largest known single-cell organisms.

“In these deep-trench environments, it’s a feast or famine existence,” said Bartlett. “There’s some benefit to being larger. An organism that can get the most nutrition from that sporadic nutrient source has an advantage,” he said.

Bartlett and the others made several other surprising discoveries, including the finding of what was likely to be a new species of sea cucumber. “Sea cucumber abundance goes up with depth, and that is even true in the challenger deep,” said Bartlett.

“This was an absolutely incredible experience. I think one of the great things we have going in oceanography, and at Scripps in particular, is that we have the opportunity to hob-nob with scientists from across disciplines. It’s all very fulfilling and dynamic and productive.”

The Birch Aquarium’s Perspectives on Ocean Science lecture series is held from 6:30-8 pm on the second Monday of every month and is open to the public. To learn more, visit, or watch past lectures online at