<P> Coordinates: 19 ° 50 ′ 9" N 66 ° 45 ′ 16" W ﻿ / ﻿ 19.83583 ° N 66.75444 ° W ﻿ / 19.83583; - 66.75444 </P> <P> The Puerto Rico Trench is located on the boundary between the Caribbean Sea and the Atlantic Ocean . The oceanic trench is associated with a complex transition between the Lesser Antilles subduction zone to the south and the major transform fault zone or plate boundary, which extends west between Cuba and Hispaniola through the Cayman Trench to the coast of Central America . The trench is 800 kilometres (497 mi) long and has a maximum depth of 8,648 metres (28,373 ft) or 5.373 miles at Milwaukee Deep, which is the deepest point in the Atlantic Ocean and the deepest point not in the Pacific Ocean . </P> <P> Scientific studies have concluded that an earthquake occurring along this fault zone could generate a significant tsunami . The island of Puerto Rico, which lies immediately to the south of the fault zone and the trench, suffered a destructive tsunami soon after the 1918 San Fermín earthquake . </P>

What is the deepest part of the atlantic ocean