Salt River Bay National Historic Park and Ecological Preserve is a unit of the National Park Service on the island of St. Croix in the U.S. Virgin Islands. It preserves upland watersheds, mangrove forests, and estuarine and marine environments that support threatened and endangered species. It also contains the Columbus Landing Site, a National Historic Landmark that is the only known site where members of a Columbus expedition set foot on what is now United States territory.