Horizon Deep

[ huh-rahy-zuhn deep ]

noun

1. the second-deepest known portion of seafloor in the world, located in the South Pacific Ocean’s Tonga Trench at a depth of 35,509 feet (10,823 meters). Compare Challenger Deep ( def ), Emden Deep ( def ).

Word History and Origins

Origin of Horizon Deep¹

First recorded in 1950–55; named after the research vessel Horizon of the Scripps Institution of Oceanography, which discovered the deep in 1952