Underwater Exploration

The invention and improvement of the submersible from about 1930 to the early 1970s opened the possibility of vastly improving our understanding of the extremes of the deep. This world is so enormous and full of mysteries that nearly every submersible dive introduces new life forms or discoveries leading to greater knowledge of the mechanics of our planet. Some of the landmark studies involving submersibles are the 1974 exploration of the Mid-Atlantic Ridge, the 1979-1980 study of the rift valley near the Galápagos Islands off the coast of Ecuador, and the 1985 discovery of the wreck of the Titanic.

In 1974, a French-American team of scientists explored the great rift in the Mid-Atlantic Ridge by using occupied submersibles and a collection of support ships. The FAMOUS Project (French-American Mid-Ocean Undersea Study) used the American submersible Alvin, the French diving saucer Cyana, and the French bathyscaphe Archimde to dive into the rift south of the Azores Islands, where geologists believe two great plates of Earth's crust, the Eurasian Plate and the North American Plate, are pulling away from each other allowing magma (molten rock) to flow into the rift and the sea floor to enlarge or spread. The research ship the Glomar Challenger was the sea-level base for the submersibles and was assisted by a small flotilla of support ships. Samples of solidified but geologically young magma were collected by manipulators on the submersibles, and over 5,200 photographs were taken in this region. Exploration would have been impossible without the submersibles; in some places, the edges of the Cyana, which was about 7 ft (2.1 m) in diameter, nearly touched both sides of the ridge and hovered over the depths of the rift that are far greater than the highest mountains on Earth's surface. Analysis of the findings from the FAMOUS Project proved that the central fissure of the rift valley is widening by about 1 in (2.5 cm) per year and added substantially to both proving and helping scientists understand plate tectonics (the motions of the massive plates comprising Earth's crust) and sea-floor spreading (the separations of those plates beneath the sea where new crustal material is made).

The 1979-1980 study of the Galápagos Rift was begun as a further study of sea-floor spreading but found it occurring in a very different environment. Mexican, French, and American scientists united efforts and discovered expanses of hydrothermal vents, which are chimney-like growths on the seabed that discharge hot springs of mineral-rich water. The water temperature of these vents is about 570°F (300°C), and the vent chimneys are about 12 ft (3.7 m) in diameter and 30 ft ( 9 m) tall. The smokey plumes of dissolved metals form deposits laden with nickel, copper, uranium, cadmium, and chromium; and the ecological community supported by the hot springs is rich in plants and animals that would have remained hidden without the camera eyes of submersibles. The hydrothermal vents and their surrounding communities proved that the deep sea is neither the barren abyss nor the realm of sea monsters of popular imagination.