Lustica Submarine Tunnels (Arza)

The Arza submarine tunnels were cut into the limestone cliffs at the southern tip of the Lustica peninsula during the Cold War by the Yugoslav People's Army navy. The tunnel complex, a set of vaulted chambers connected to the open sea, was designed to shelter submarines and patrol boats from air surveillance and weather, with room for multiple vessels to moor inside the solid rock. The tunnels were part of the wider Yugoslav defensive system protecting the Bay of Kotor, which included the naval base at Tivat (now the Porto Montenegro marina) and the outer fortifications on Mamula and the Prevlaka peninsula. After the Yugoslav navy was disbanded in the 1990s the tunnels were decommissioned and eventually opened to civilian boat tours.

Most visits happen as part of the standard Lustica boat tour that also covers Žanjic beach, the Blue Grotto and Mamula island. Tour boats enter the tunnel entrances, glide through the vaulted chambers, notably cooler and darker than the open bay, and exit back to daylight. The tunnel interiors are large enough for full-sized small boats but small enough that the acoustic effect of engines against stone is pronounced. Swimming inside the tunnels is permitted on most tours.

Above the tunnels on the clifftops sit the ruins of the Arza fortress, a Venetian coastal fortification progressively expanded by the Austro-Hungarians. The fortress is partially accessible on foot from the small coastal path but requires a scramble in places. The combined submarine tunnels + fortress visit takes 30 to 45 minutes as part of a half-day boat tour from Herceg Novi marina.