Vast fields of sea cucumbers and huge tendrils of bacteria that live without the energy of the sun have been filmed at depths of over 26,000 feet beneath the ocean surface in Chile's Atacama Trench.
Caladan Oceanic Founder Victor Vescovo and Osvaldo Ulloa, of the Department of Oceanography at the University of Concepcion, Chile, dove over 26,000 feet below the surface of the Pacific Ocean off the coast of Peru and Chile and reached the deepest point in that part of the ocean for the first time ever on January 24.
The life they found there astounded them.
"They're called holothurians, also known as sea cucumbers," Vescovo, a former commander in the U.S. Navy, told Newsweek. "We saw probably more sea cucumbers at the bottom of this trench than I have seen at any other trench. We believe that's because the amount of nutrients that flow into the Atacama basin are much higher than in most other ocean trenches.
"I even characterized the 'fields' of holothurians that I saw as almost looking like one of the pastures that I see with the cows in Texas. They were everywhere, feasting on the food that had drifted down from the higher parts of the ocean. It was great to see all these creatures in all their forms."
Vescovo's company, Caladan Oceanic, worked with several top scientists in the Chilean scientific community including Marine Biologist Ruben Escribano from the University of Concepcion for the expedition. The company provided them with the hardware used in the dives—a two-man vessel called Limiting Factor capable of taking humans to some of the most extreme environments on Earth.
Along with sea cucumbers, the team found huge "mats" of bacteria that are some of the only known organisms on Earth to survive without the sun's energy. They do so via a process called chemosynthesis, which allows lifeforms to get the energy they need to survive directly from the methane and minerals produced at the bottom of the ocean.
"I think the bacterial mats and evidence of chemosynthesis in fissures of the rocks is one of the major scientific findings of this expedition, Vescovo said. "And we saw these tendrils of bacteria, the largest I've ever seen, brilliant gold in color ... Dr Ulloa was just shocked by them. Just so excited.
"Before we started our expeditions in 2018 there was a lot of debate about how prevalent chemosynthesis was. There were only a handful of observations. But I have personally seen evidence of chemosynthesis with my own eyes in multiple trenches all over the world. It's an unusual form of life and it was great to see."
The dive to the Atacama Trench is one in a series of dives to Earth's ocean trenches carried out by Vescovo and his team. Ocean trenches represent the deepest known points on Earth. They are v-shaped depressions that extend down beyond the seafloor.
Vescovo dove all five of the deepest points of Earth's oceans in 2018 and 2019. This included the Challenger Deep, in the Maraina Trench, which extends around 36,200 feet below the ocean surface.
As for co-piloting a mission to the most extreme environments on the planet, Vescovo said: "I don't get scared at all. Even when I first started diving in the submersible. I have such confidence in its design and construction that I don't get overly anxious, especially not anymore.
"I've done around 70 dives, most of them greater than 6,000 meters, so for me it's like when I step into an aircraft ... I just mind the electronics and mechanics and if something comes up you deal with it."
