Dungeness Spit, thought to be the world’s longest natural sand spit, juts out from the Olympic Peninsula in Washington State. It is part of the Dungeness National Wildlife Refuge and is as little as 50 ft (15 m) wide in places. In addition to its great length, the spit has a complex shape, the result of seasonal changes in wind and wave direction. During part of the year, these bring sandy sediments from the northwest, and at other times from the northeast. The resulting pattern of sedimentation has created a large sheltered coastal area, providing refuge for many shorebirds and waterfowl, which nest along the beach, and for Pacific harbor seals. The tidal flats nourish a variety of shellfish, and the inner bay is an important nursery habitat for several salmon species.