A spit is a peninsula of loose sediment deposited by longshore drift. Longshore drift occurs when the prevailing wind is not perpendicular to the shore, so the incoming waves tend to move sediment along the shoreline away from the wind. When the shoreline bends abruptly, the moving sediment doesn’t follow the bend and keeps going straight. Depending on other factors such as water depth and currents, it can build out to form a peninsula known as a spit.
Dungeness Spit is the longest in the United States, spanning over five miles. It’s open for hiking on the seaward side (Dungeness Bay, on the leeward side of the spit, is a wildlife refuge and closed to hiking). Walking in the area is difficult, as the ground is composed of mostly loose sand and cobbles, and therefore slow. It’s especially important to check tide tables before embarking on a long hike, especially out to the lighthouse.
The spit becomes awash at high tide, and it’s covered with large driftwood logs that become exceedingly hazardous when thrown around by the surf.