A ship known for its missions to raise awareness about the problem of marine debris sank Sunday in the Oakland Estuary, authorities said. The Kaisei, a large double-masted sailing vessel, sank at a dock behind the Nob Hill Foods grocery store in Alameda shortly after 6 p.

Salvage crews on Monday were trying to refloat a large sailing ship that sank Sunday night while docked at the Oakland Estuary. The boat, part of an ocean cleanup project, is now presenting a cleanup problem of its own.