La Grotta dell' Arsenale

Useful Information

Location: Capri, southern coast. Accessible only by boat.
(40.5460895808872, 14.2415505793001)
Open: no restrictions.
Fee: free.
Classification: Speleologysea cave
Light: bring torch
Dimension: L=4 m, W=3.5 m, H=1.5 m.
Guided tours: n/a
Photography: allowed
Accessibility: no
Address: Azienda Autonoma Soggiorno Cura E Turismo, Via Padre Serafino Cimmino, 1, 80073 Capri NA, Tel: +39-081-837-0424.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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1777 excavations revealed Roman ruins.
1853 description by Ferdinand Gregorovius.


The Grotta dell'Arsenale (Arsenal Cave) is a small cave on the island of Capri. It was used by the military during the Middle Ages as an arsenal, hence the name. It is only a single chamber with a diameter of 4 m, but it has a big historic importance. It was used by the Romans, probably as a depot or naval station. During excavations the remains of Roman walls, a floor of coloured marbles, and some iron fragments were discovered.

The strange thing is, that the cave is today located 2.4 m above the sea, in southerly gales, waves hit it so forcefully to render it unusable as a storehouse. The cave was formed as a sea cave by the erosion of the waves. At this time it was obviously located at sea level. But in Roman times, 2,000 years ago, it was a naval station, the walls were built when the cave was higher above the sea than it is today. In other words, this cave is proof for an uplift of several meters and a subsequent subsidence of several meters. This discovery was quite new and was published in the Geographical Journal of the Royal Geographical Society in 1903. The bay of Naples has numerous different up- and down movements as a result of volcanic activity. It is explained by pressure building up in the magma chamber below.