In the area of Cala Bassa, particularly in Caló d'en Rafal, you’ll find the largest sea cave on the island of Ibiza. It’s so huge that even large vessels longer than 40 metres can enter it. This cavity has a mouth about 15 metres high at the entrance and a ceiling about 10 metres high inside it.

Once inside it, if you look back, you’ll realise it has a hexagonal shape that was not quite noticeable at the entrance.

Nautical charts and old maps indicate that the name of this geological formation is Sa Cova (‘The Cave’), and its origin needs no further discussion.

Inside this cave, its walls are porous, just like its ceiling. On the days after it rains, fine, crystal-clear rivulets of water randomly trickle into the sea.

The perimeter walls that are more exposed to wave action have an intriguing bluish-purple edge. This beautiful edge that looks like a lovely wavy blue Roman frieze is produced by the oxidation of a substance secreted by sea snails, which slowly crystallises on the rock when the waters are calm. This substance, called Tyrian purple, was greatly prized in Roman times. It was used to dye the distinctive togas of the Empire’s upper classes and to make the dyes intended for the exclusive use of Roman senators and emperors.

This sought-after substance was so valuable in the Roman Empire that simply discovering an area or the remains of one that was teeming with these small molluscs was enough reason for invasion, with the consequent war by order of the Senate and the reigning Emperor. This was because since the time of Augustus at the beginning of the first century AD, Tyrian purple fetched a price higher than gold.

Smooth sailing!