Ship John Shoal Light is an offshore lighthouse in Delaware Bay marking the north side of the ship channel near Bombay Hook National Wildlife Refuge. The shoal took its name from the John, lost there in 1797 after running aground on a voyage from Hamburg to Philadelphia. After early plans were altered by failures of screw-pile construction, Congress funded a more durable caisson lighthouse in 1873. Delays, harsh winter conditions, and even a detour to the 1876 Centennial Exposition slowed completion until 1877. Later protected with riprap, the light was automated in 1973 and remains notable for its unusual route to service.