The ocean's greatest depths once were believed to be devoid of life. But in the past 25 years, intrepid explorers, diving to the seafloor in high-tech submersibles, have disproved that notion. They have discovered that a number of unusual organisms inhabit some areas of the deep sea -- at underwater geysers called hydrothermal vents.

Here, over a mile beneath the ocean's surface, live dinner-plate-sized clams reeking of sulfur, towering tubeworms resembling giant lipsticks, ghost-white crabs prowling for prey, pinkish eel-like fish, and the microscopic bacteria that hold together this strange web of life.

Currently, scientists at the University of Delaware Graduate College of Marine Studies are exploring hydrothermal vent sites to learn more about this "extreme" environment and its unique community of organisms.

After all, vent dwellers thrive under some of the most demanding conditions on the planet. They live in a world of total darkness. They are constantly bathed in toxic chemicals that rocket out of the vents. And many of them can withstand a broad range of temperatures.

Most of the deep sea is only a few degrees above freezing -- except at hydrothermal vent sites. Some organisms that live around the vents can survive temperatures close to boiling.

What's more, the pressure exerted on these organisms from the weight of the vast ocean above is more than 250 times the pressure we feel on land. That's the equivalent of one person trying to hold about a dozen jumbo jets!

Turn the page and learn more about hydro-thermal vents, the creatures that inhabit them, the technology that makes deep-sea research possible, and the discoveries that UD marine scientists are making. Let's dive in!