Ocean Depths

Challenger Deep, located in the Mariana Trench in the western Pacific Ocean, reaches approximately 36,000 feet (about 11,000 meters) below sea level, making it the deepest known point on Earth.

Swiss oceanographer Jacques Piccard and U.S. Navy Lieutenant Don Walsh descended to the bottom of the Challenger Deep on January 23, 1960, in the bathyscaphe Trieste.

As of recent estimates, only about 25% of the ocean floor has been mapped to modern standards using high-resolution sonar. Much of the deep ocean remains unexplored and unmapped.

The aphotic zone (also called the midnight zone) is the part of the ocean where no sunlight reaches, generally below about 3,300 feet (1,000 meters). 'Aphotic' means 'without light.'

Bioluminescence is the production of light by living organisms through chemical reactions. About 76% of deep-sea creatures use bioluminescence to attract prey, find mates, or escape predators.

The Pacific Ocean is the deepest ocean with an average depth of about 14,040 feet (4,280 meters). It is also the largest and oldest of the world's ocean basins.

Hydrothermal vents are often called black smokers because they emit dark plumes of superheated, mineral-rich water that looks like black smoke. They can reach temperatures above 700°F (370°C).

The Great Barrier Reef off the coast of Australia is the largest structure made by living organisms. Stretching over 1,400 miles (2,300 km), it is built by billions of tiny coral polyps.

The midnight zone (bathypelagic zone) begins at about 1,000 meters (3,300 feet) depth. At this depth, no sunlight penetrates and temperatures hover just above freezing.

The Mid-Atlantic Ridge is an undersea mountain range that runs down the center of the Atlantic Ocean for about 10,000 miles. It is formed where tectonic plates are spreading apart.

The anglerfish has a bioluminescent lure called an esca that dangles from a modified dorsal spine on its head. It uses this glowing lure to attract prey in the pitch-dark deep ocean.

Ocean tides are primarily caused by the gravitational pull of the Moon and, to a lesser extent, the Sun on Earth's oceans. The Moon's proximity to Earth makes it the dominant tidal force.

The hadal snailfish (Pseudoliparis swirei) has been found at depths exceeding 26,000 feet (8,000 meters) in the Mariana Trench, making it the deepest-living fish ever recorded.

The Great Blue Hole is a giant marine sinkhole off the coast of Belize, over 980 feet (300 meters) across and 410 feet (125 meters) deep. It was formed during ice ages when sea levels were lower.

At the bottom of the Mariana Trench, the water pressure is over 15,000 pounds per square inch — more than 1,000 times the atmospheric pressure at sea level. Deep-sea organisms have adapted to withstand this crushing force.