The strangest, most seemingly alien place on Earth, at least to surface dwellers such as humans, has to be the deep ocean. Back in the mid-1970s, scientists discovered a particularly strange spot — the hydrothermal vents that penetrate a mile-and-a-half (2 kilometers) into the ocean floor near the Galapagos Islands in the South Pacific.
Inside the vents, water heated by volcanic activity sometimes reaches 750 degrees Fahrenheit (400 degrees Celsius), thanks to the intense pressure from the water above that keeps it from boiling away. That hot water dissolves metals and salts as it moves along rocks, eventually rising and pouring out into the bitter cold, pitch-black darkness. The vents also spout hydrogen sulfide, a gas which is poisonous to most land-based life. Even so, the vents are home to bacteria, which have evolved to use the seeming poison as an energy source. Scientists think these microbes may closely resemble the earliest life-forms in Earth's oceans [source: Trivedi].