river pilot

A river pilot is a specialist who navigates vessels through particular stretches of river, possessing detailed knowledge of local channels, currents, shoals, and hazards that charts alone cannot convey.

Unlike ocean pilots who guide ships into harbors, river pilots often travel long distances with vessels, sometimes hundreds of miles: The river pilot boarded at New Orleans to guide the steamboat upriver.

Mark Twain famously worked as a Mississippi river pilot before becoming a writer.