The Geiyo Islands around the Shimanami Kaido bridge network are famed for some of the world’s fastest currents, a result of the complex topography of the closely clustered archipelago. In times when shipbuilding and maneuvering technology was far less advanced, seafarers knew this island chain as a daunting obstacle that was exceptionally difficult to navigate. They relied on the Murakami Suigun for their expert knowledge of the tides and skills as ship pilots. A powerful local group sometimes called pirates or a navy, the Murakami Suigun ensured safe passage, maintained order, and facilitated trade through these waters. On this route, guntû sails between islands these legendary sailors called home.