Hurst Spit is a one-mile-long (1.6 km) shingle bank near the village of Keyhaven, at the western end of the Solent, on the south coast of England. The spit shelters an area of saltmarsh and mudflats known as Keyhaven and Pennington marshes. At the end of the spit is Hurst Castle, an artillery fortress originally built on the orders of King Henry VIII, and much enlarged in the 19th century. Hurst Point Lighthouse was built on the end of Hurst Spit in the 1860s.

The Solent is a strait between the Isle of Wight and mainland Great Britain; the major historic ports of Southampton and Portsmouth lie inland of its shores. It is about 20 miles long and varies in width between 2+1⁄2 and 5 mi, although the Hurst Spit which projects 1+1⁄2 mi (2.4 km) into the Solent narrows the sea crossing between Hurst Castle and Colwell Bay to just over 1 mi (1.6 km).