The Nautilus is exploring and studying the biology, geology and archeology along the ocean floor.
The circular pool is about 100 feet wide, 12 feet deep and 3,300 feet below the surface of the Gulf of Mexico. The dense, warm brine water sits at the bottom. Pockets of salt and methane are released from beneath.
Mussels line the walls helping to hold together the canyon-like formation. Researchers noted the the number of preserved crustaceans and hypothesized if they mistakenly wandered in or knowingly went in to die.
"It's warm, but super salty," Scott Wankel, a biogeochemist at the Woods Hole Oceanographic Institution, said, noting it's about 65 degrees while the surrounding water is 39. "When they fall in they die and get pickled and preserved."