Lyme Bay is an area of the English Channel off the south coast of England. The south western counties of Devon and Dorset front onto the bay. The exact definitions of the bay vary. The eastern boundary is usually taken to be Portland Bill on the Isle of Portland, but there is no consensus over the western boundary. The broadest definition places the boundary at Start Point, and therefore includes Tor Bay and Start Bay as areas within Lyme Bay. A narrow definition gives the eastern boundary as Hope's Nose headland, excluding Tor Bay and Start Bay, used for example by the Water Framework Directive definitions of waterbodies. Other definitions place the boundary somewhere between these two points, including at Dartmouth (used by the Lyme Bay West Marine Character Area) and Berry Head.