Exploring the deep ocean floor [This Dynamic Earth, USGS] "Once it was thought that life had to have sunlight to exist.  We believed high temperatures would cook, instead of sustain life.  Read these quotes from the USGS:
In 1977, scientists discovered hot springs at a depth of 2.5 km., on the Galapagos Rift (spreading ridge) off the coast of Equador.  This exciting discovery was not really a surprise."