The Balearic Islands are world-renowned for their sunny landscapes and crystal-clear waters. However, beneath this idyllic surface lies another, lesser-known world. A network of natural caves, secret passages in ancient monasteries, military shelters, and defensive tunnels forms an integral part of the archipelago’s history, revealing its past from an unexpected perspective.
For centuries, Menorca, due to its strategic location in the Mediterranean, was the subject of rivalry between the British, French, and Spanish. This rich military history is reflected in the island’s defensive architecture, much of which lies underground. At the entrance to the port of Maó stands Castillo de San Felipe, which holds one of the most extensive networks of military tunnels in the islands. Built in the 16th century and expanded by the British in the 18th, it once had more than seven kilometers of underground passages used to fend off attacks, shelter troops, and store supplies. Today, guided tours along these tunnels offer a glimpse into the living and combat conditions of the past.
Nearby, on the La Mola peninsula, stands the Fortaleza de Isabel II, adding to the island’s defensive heritage. While its main structure rises above ground, the fortress also includes galleries and shelters carved into the rock, providing fast and discreet access to key points. Although it never saw combat, the fortress remains a testament to the efforts to protect one of Europe’s most important natural harbors. Beyond its military sites, Menorca impresses with its geological heritage. The Cova de s’Aigua in Cala Blanca combines archaeology and natural beauty. This cave, hidden beneath a residential area, features a crystal-clear underground lake stretching 60 meters, with a history dating back more than 5,000 years.
Mallorca attracts visitors with its famous caves, such as Cuevas del Drach or Artà, yet the island also hides lesser-known gems. Among them are the Cuevas de Campanet, discovered by chance in 1945 during the digging of a well. Unlike their more touristic counterparts, Campanet offers a peaceful journey among stalactites and stone curtains in a more natural setting. The island’s history has also found its place underground in monasteries. In sanctuaries such as Monasterio de Lluc in the Serra de Tramuntana mountains or Santuario de Cura, there are subterranean chambers, crypts, and passages that have been used for centuries for spiritual needs, storage, or as escape routes.
On Ibiza, the underground world is linked not to war but to spiritual heritage. The Cova des Culleram cave in the north of the island functioned as a shrine from the 5th century BC to the 2nd century AD and was dedicated to the goddess Tanit. Discovered in 1907, it contained over 600 terracotta figurines, confirming its religious significance in the Punic-Carthaginian world. There are also other, smaller caves associated with local legends and used as temporary shelters.
Formentera, due to its size and geology, does not possess large underground structures, but it has preserved small coastal caves and dry-stone shelters once used by fishermen and shepherds. An example is the Cova Foradada by the sea, which served as a resting place for travelers. These subterranean sites enrich the history of the Balearic Islands, revealing their hidden heritage and demonstrating a deep connection between their visible landscapes and the past.
