The robot's lights revealed a world that is otherwise in complete darkness, but is alive with animals that are both delicate and colorful.
On its slopes they found forests of giant coral. "The coral are taller than I am, maybe twice as tall as I am, maybe three times as tall as I am," said marine biologist Greg Cailliet.
Also hidden in this treasure trove beneath the Pacific, biologists have found what they call a "mystery mollusk." It's an animal they know so little about, it doesn't even have a name yet.
"It's pretty amazing that something that could be down maybe 1,000 to 3,000 meters, over a mile deep, living in two to three degrees centigrade, with no light whatsoever," Cailliet said. "We're down there with lights on so we tend to forget that they really can't see us."
A bright red sea cucumber, of a species not yet identified, was also found. A halosaur -- a fish with a needle-point nose -- was discovered nearby. It was not previously known to live in waters near California. And a little, rarely-seen red fish known as a "sea toad" was spotted.
But not everything the scientists discovered is from another world.
They also found a milk bottle and other litter almost two miles down.
Perhaps the creatures that live down there knew something about man, long before he knew anything about them.