The Tongue of the Ocean is the name of a deep oceanic trench in the Bahamas separating the islands of Andros and New Providence. The depth of the water drops from roughly 115 feet (35 m) along Andros' east offshore barrier reef to over 6,000 feet (1.8 km), and the drop is roughly 100 miles (160 km) long.
This channel and the Providence Channel are the two main branches of the Great Bahama Canyon, a submerged geological feature formed by erosion during periods of lower sea level. During their early history the Tongue of the Ocean and the Providence Channels were broad, relatively shallow basins flanked by growing carbonate banks. As the Blake-Bahama platform subsided, sedimentation kept pace with subsidence on the banks, but not in the basins.
A joint United States/United Kingdom Agreement signed in 1963 with the concurrence of the Bahamian Government, enabled the United States to develop this area of water and certain territory on the east coast of Andros Island, readily accessible to the TOTO, and there install equipment to build three offshore test ranges. Under this agreement, the Royal Navy has equal access to the test facility.
Taking advantage of the deep water close to shore, the United States has operated the Atlantic Undersea Test and Evaluation Center (AUTEC) on Andros since 1965 to research anti-submarine warfare for the Western Alliance using live targets and synthetic torpedoes in a realistic environment.
Today, AUTEC employs over 400 Americans and 170 Bahamians. The 1983 bilateral lease agreement provides for the use of land sites, airspace and seabed for a payment of $10.8 million a year.