Neptune's Grotto

Neptune's Grotto (Italian: Grotta di Nettuno; Catalan: Cova de Neptú) is a stalactite cave near the town of Alghero on the island of Sardinia, Italy. The cave was discovered by local fishermen in the 18th century and has since developed into a popular tourist attraction. The grotto gets its name from the Roman god of the sea, Neptune.

Source: Wikipedia (CC BY-SA 4.0) — https://en.wikipedia.org/wiki/Neptune%27s_Grotto