-
President Thomas Jefferson signs a bill authorizing the United States Coast Survey.
-
James Alden discovers the first known submarine valley, California's Monterey Canyon.
-
Charles Wyville Thomson, dredging from the H.M.S Lightning, finds sea life at 4,389 meters (14,400 feet), shattering previous theories that the sea was lifeless below 549 meters (1,800 feet).
-
The Titanic sinks after hitting an iceberg, killing 1,500 people. The tragedy led to efforts to develop an acoustic device to find objects ahead of a vessel.
-
Reginald Fessenden uses an oscillator to bounce a signal simultaneously off an iceberg and the seafloor, the first acoustic exploration of the seas.
-
The German Meteor expedition surveys the South Atlantic with echo sounders, proving the continuity of the Mid-Atlantic Ridge.
-
William Beebe is lowered in a tethered bathysphere to 923 meters (3,028 feet). He and partner Otis Barton pioneered manned exploration of the ocean.
-
Jacques Cousteau and Emile Gagnan modify a demand breathing regulator to engineer the Aqua-Lung, forever changing the course of human interaction with the sea.
-
The French research submersible FNRS-3 descends to 4,041 meters (13,257 feet) off the coast of West Africa, piloted by Georges Houot and Pierre Willm, inaugurating use of manned, untethered, research submersibles.
-
The U.S. Coast and Geodetic Survey ship Pioneer, in a joint project with the U.S. Navy and the Scripps Institution of Oceanography, tows the first marine magnetometer and finds magnetic striping on the seafloor off the West Coast. The discovery adds a key element to the theory of plate tectonics.