Early American submarine, involved in a fatal accident in the 1920s.

On March 12, 1920, the H-1 was on exercises near Santa Margarita Island, CA, when she became grounded on a shoal. The 25 crew members attempted to swim to shore, but only 21 made it. Among the deceased was the vessel's commanding officer. After the surviving crew members were rescued, the repair ship U.S.S. Vestal (later among the attacked ships at Pearl Harbor) was dispatched to attempt removal of the sub from the shoal. Although the Vestal was able to get the H-1 off the rocks, the submarine sank less than an hour later. Further salvage attempts were called off.

The H-1's whereabouts remained shrouded in mystery until 1992, when the lost sub was rediscovered on the ocean floor near the spot where it originally ran aground.