Cuevas del Drach

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 and one of the main attractions on Mallorca. The visit ends with a classical concert performed by four musicians on a boat.