Pipeline is a surf reef break located in Hawaii, off Ehukai Beach Park in Pupukea on O'ahu's North Shore. Pipeline is notorious for huge waves which break in shallow water just above a sharp and cavernous reef, forming large, hollow, thick curls of water that surfers can tube ride. There are three reefs at Pipeline in progressively deeper water farther out to sea that activate according to the increasing size of approaching ocean swells.(Wikipedia)