In 1977, scientists made a stunning discovery on the bottom of the Pacific Ocean: vents pouring hot, mineral-rich fluids from beneath the seafloor.
The mid-ocean ridge occurs along boundaries where plates are spreading apart.
As much as one half of the oil that enters the coastal environment comes from natural seeps of oil and natural gas.
Ocean trenches are steep depressions exceeding 6,000 meters in depth, where old ocean crust from one tectonic plate is pushed beneath another plate.
Mountains rising from the ocean seafloor that do not reach to the water's surface.