沙咀（沙嘴）是一种沿岸形成的沉积地形，沙咀是一种沙洲或海滩，常在小海湾、海湾、溺湾或河口旁形成，**东北角双溪河位于福隆海水浴场的出海口就形成一个典型的沙咀地形。

A spit or sandspit is a deposition bar or beach landform found off coasts. It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift and longshore currents. The drift occurs due to waves meeting the beach at an oblique angle, moving sediment down the beach in a zigzag pattern. This is complemented by longshore currents, which further transport sediment through the water alongside the beach. These currents are caused by the same waves that cause the drift.