They turned off their lights at about 2,900 feet, and the ocean became a sparkling firefly world.
"Sunlight doesn't go any deeper than this," remarked a scientist aboard the deep-diving submersible Alvin."But we do," writes Rick Gore for National Geographic. "In fact we are making a luminous blue tunnel as we plunge through bioluminescent bacteria along our path."
The creatures in the water glow "to improve their odds of being eaten," the scientist explained. "Being ingested doesn't faze a bacterium."
Tiny animals eagerly offering themselves as food are but one of the strange phenomena Gore discovered while researching his story about California's Monterey Bay, site of the largest submarine chasm along the continental United States and arguably the richest ecosystem on the West Coast.
Monterey Bay is a "poem of the sea," Gore writes, "a complex dream with internal rhythms that confound and astonish."
Cruising a canyon wall with lights on again, the small, three-person craft passed brilliant red medusae. Lobate ctenophores, some of which look like pulsating pieces of Steuben glass, became prisms in the glare.
"How odd that life in these lightless depths is so often colorful," Gore says.
Colorful and odd. Some anglerfish males in the bay are much smaller than the females they must fertilize. Once one locates a mate, he bites into her. Their bodies fuse, and the male degenerates into nothing but gonads and a surrounding lump of tissue - a permanent, portable sperm supply.
Another surprising life form found in the bay is the larvacean, an animal no longer than a finger, which spins around itself a fragile web of mucus sometimes as large as a person.
The creatures circulate water within that mucous shell. Like fine nets, feeding filters trap detritus (disintegrated debris). When the animal dies or leaves home, its house falls apart, creating a snow of sinking mucus.
Besides carrying food to bottom-dwellers, larvaceans may provide a vital service to all life on the planet, some scientists now believe.
Scientists who study the flow of carbon through the biosphere have been puzzled. They cannot find all the excess carbon dioxide that their calculations say humans, by burning fossil fuels, are pumping into the atmosphere. Even though carbon dioxide levels are rising ominously, some process seems to be moderating the buildup.
One way nature removes carbon dioxide is through photosynthesis in the oceans. Plankton turn dissolved carbon dioxide into organic matter, which later may be eaten by animals. The animals then return to the atmosphere, through their own respiration, much of the carbon the plankton removed. Organic matter also falls on the seafloor, where it is either buried or eaten by creatures that are unlikely to take it back near the surface.
"Larvacean houses carry down more organic matter than suspected," Gore writes. "Since larvaceans may inhabit much of the midwater of the oceans, these unsung bags of mucus would be playing a significant role in helping the biosphere keep carbon dioxide under control."
Much of the life found in the bay waters is on display in the Monterey Bay Aquarium, which opened in 1984 with an investment of about $55 million from one of the bay's most influential figures, David Packard of the Hewlett Packard electronics company.
Housed in structures mimicking the site's former cannery buildings made famous by John Steinbeck's 1945 novel, "Cannery Row," the aquarium had 1.7 million visitors in 1989.
Packard himself promoted dynamic displays. At the Rocky Shore exhibit, a crowd stands behind a window studying a peaceful rock face adorned with sea anemones and limpets. Without warning, a foaming wave blasts through a hole in the rock, bringing startled squeals from spectators. Seconds later, just as along the surf-battered Monterey coastline, peace returns.
The aquarium staff invented a surge machine, which gives life to the aquarium's most popular exhibit. It represents one of the bay's most striking natural wonders, the Kelp Forest.
A huge aquamarine tank more than 30 feet deep swirls with fish and sways with the golden stalks of the world's grandest seaweed. It re-creates the underwater spectacle that draws hundreds of divers to Monterey on weekends.
"As you enter the aquarium, the cathedral aura of the Kelp Forest, with sunlight streaming down from above, turns your head and pulls you over, bidding you to slow down and meditate on the majesty that lies hidden just offshore," Gore writes.
"We are all working on the same question," one aquarium researcher told Gore. "How does Monterey Bay work?"