county, east-central New Jersey, U.S., bounded by the Metedeconk River to the north, the Manasquan River to the northeast, and the Atlantic Ocean to the east. It comprises a coastal lowland area and, in addition to the Metedeconk and Manasquan, is drained by the Toms and Forked rivers. The county contains many lakes, wildlife refuges, and recreational areas, including Island Beach and Barnegat Lighthouse state parks—both of which are located on a barrier beach between Barnegat Bay and the ocean. Forested areas contain shortleaf pine with stands of oak.

Early inhabitants of the region were Delaware Indians. In the 19th century the county was known as a major centre of cranberry production. The U.S. Navy tested dirigibles in Ocean county until the German airship Hindenburg exploded at Lakehurst on May 6, 1937, damaging the industry's reputation.

The county was created in 1850 and named for its proximity to the Atlantic. The principal communities are Brick, Lakewood, Jackson, and Toms River, which is the county seat. Tourism is the mainstay of the economy. Area 636 square miles (1,648 square km). Pop. (2000) 510,916; (2007 est.) 565,493.