Ocean scientists estimate that there are at least 10 million undiscovered plant and animal species living in the ocean. In volume terms, 95 percent of the ocean has never been explored and almost all of the biological samples taken from the ocean come from the shallower half.
Scientists know very little about the ocean’s deeper portions, especially those more than 650 feet (200 meters) below the surface, which is the depth to which sunlight penetrates. Beyond this depth, photosynthesis cannot take place.
The deepest recorded ocean depth is 36,201 feet (11,034 meters) and the deepest manned submersible dive was 35,800 feet (10,911 meters) into the Mariana trench by the submersible “Trieste” in 1960.