The average depth of the ocean floor is 13,124 feet (4,000 meters). The average depth of the four major oceans is given below:

There are great variations in depth because the ocean floor is often very rugged. The greatest depth variations occur in deep, narrow depressions known as trenches along the margins of the continental plates. The deepest measurements made—36,198 feet (11,034 meters), deeper than the height of the world’s tallest mountains—were taken in Mariana Trench east of the Mariana Islands. In January 1960, the French oceanographer Jacques Piccard (1922–2008), together with the U.S. Navy Lieutenant David Walsh, took the bathyscaphe Trieste to the bottom of the Mariana Trench.

^*This is the the deepest point that the Triest reached, but there have been soundings as deep as 36,198 feet (11,034 meters).