This article looks at the main Izumo myths found in the Kojiki (Record of Ancient Chronicles) from the perspective of the sea. It discusses how the sea gods in the Yamata no Orochi myth, the Hare of Inaba myth, the Ne no Katasukuni myth, and the Go Shozan Engi myth were deeply connected with on-land agricultural life, how myths from the South Pacific came to Izumo, and how Izumo's mythical universe depends on a maritime base.