Cuevas del Drach are caves located next to city of Porto Cristo in Mallorca, Spain. It contains one of the largest underground lakes in the world. Once you reach the underground lake (Lake Martel), you can see musicians on the boat playing classical music.
Known as Waiahuakua, this is the second longest sea cave in the world, stretching 1,155ft. It is known as the Sacred Water Cave and as the Double Door cave – as it has both an entrance and an exit. Kayak tours run through the cave to allow visitors a close-up view of the caverns huge length. A fissure in the roof of the volcanic rock allows water to gush into the amazing cavern.