The Caves of Drach (modern Catalan spelling: ; ; ) are four great caves that are located in the island of Majorca, Balearic Islands, Spain, extending to a depth of 25 m and reaching approximately 4 km in length. They are in the municipality of Manacor, near the locality of Porto Cristo. They were first mentioned in a letter dated 1338. The four caves, called Black Cave, White Cave, Cave of Luis Salvador, and Cave of the French, are connected to each other. The caves have formed by water being forced through the entrance from the Mediterranean Sea, and some researchers think the formation may date back to the Miocene Epoch. There is an underground lake situated in the caves called Martel Lake, which is about 115 m in length and 30 m in width, and its depth varies between four and twelve meters. It is named after the French explorer and scientist Édouard-Alfred Martel, considered the founding father of speleology, who was invited to explore the cave 1896. While German cave explorer, M.F. Will, had mapped the White and Black cave in 1880, Martel found two more caves, as well as the underground lake. The caves are open to the public for a fee, and are one of the main tourist attractions on Mallorca. The visit typically ends with a classical music concert, performed by a small orchestra of musicians on a fleet of small row boats. The caves are such an integral part of the tourism industry, that its closure, even if temporary, is seen by the locals as a bad sign for the economy. References Show caves in Spain Landforms of Mallorca Tourist attractions in Mallorca Landforms of the Balearic Islands Bien de Interés Cultural landmarks in the Balearic Islands Caves of Spain