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. Geology The east of the bay is part of a World Heritage Site, the Dorset and East Devon Coast, which is also known as the Jurassic Coast, named for its Jurassic geology. History Many of the earliest discoveries of dinosaur and other prehistoric reptile remains were in the area surrounding Lyme Regis and Charmouth. Notable among these were the discoveries made by self-educated palaeontologist and fossil collector Mary Anning, in the 1820s. The weather in the bay is temperate by English standards, and far more temperate than many other places at a similar latitude. The reason for this is the warming action of the Gulf Stream. The area along the coast of Lyme Bay is thus a popular holiday destination. On 22 March 1993, four schoolchildren died in what is known as the Lyme Bay kayaking tragedy. Lyme Bay was the site of Exercise Tiger, a practice run for the D-Day invasion of France in 1944, using the beach called Slapton Sands near Slapton, Devon as the practice landing zone. The operation was intercepted by German E-boats that attacked the landing craft, killing 749 American Army and Navy personnel in the middle of Babbacombe Bay, the most unbounded western sub-bay of the bay. A ship commissioned in 2007 for the Royal Fleet Auxiliary carries the name: RFA Lyme Bay. Underwater Much of the subsurface realm is locally unspectacular, without underwater rock cliffs painted with a riot of colour nor very clear water. The reefs in Lyme bay are mostly low lying and the waters tend to be fairly gloomy and turbid. As an essentially large, open, sandy