How Deep is the Sound?

The average depth of Long Island Sound is a shallow 63 feet. If dropped into the Sound at this depth, the Statue of Liberty would still have 86 feet exposed above the water (not including the pedestal).

Why do we say that’s shallow? It’s shallow compared to the average depth of the Atlantic Ocean. It has an average depth, with its seas, of 10,925 feet (3,300 meters) and a maximum depth of 27,493 feet (8,380 meters) in the Puerto Rico Trench, north of the island of Puerto Rico. The Hudson Canyon, a submarine canyon, which runs from the Hudson River- New York/New Jersey Harbor to 400 nautical miles offshore, reaching depths of 3,500 meters (10,500 feet). Source: Marine Conservation Institute.

The depths of the Sound vary greatly by location. In the western Sound, with its smooth sandy seafloor, the depths can be well under 20 feet. In the central Sound, it’s around 65 feet, while the eastern Sound is deep, dipping to 350 feet at the Race with a bottom that is mostly rocky.

The Sound Facts series is adapted from Sound Facts: Fun Facts About Long Island Sound, a Connecticut Sea Grant publication.