Fascinating marine creatures exist in some of the ocean's deepest waters where no light reaches. They survive because they cluster around hydrothermal vents--milky-blue plumes of hot water pouring out of ocean bottom openings, which are shaped like chimneys or mounds. Valuable nutrients spew out of these spouts, enabling creatures to thrive and build entire colonies. Clams, worms, and other marine life are able to flourish in absolute darkness, even when no food is available, because they feed off the mineral-rich water.

In 1974, American oceanographers detected the first sign of these "hot-spots" while gauging the water temperature in a region called the Galapagos Rift on the Pacific floor. Temperatures at these spots measured between 35°-39° F (2°-4° C). Subsequent temperature readings have measured the water at more than 662° F (350° C). Alvin, a small research submarine sponsored...