Hidden Gems - fortresses, caves and old military tunnels accessible by boat

02 Dec, 2025

Hidden Gems - fortresses, caves and old military tunnels accessible by boat

The Bay of Kotor is known as the southernmost fjord in Europe. In addition, what makes it famous is its crystal water, unfathomable mountains and the reputation of one of the most beautiful bays in the world. Inside the Bay there are a lot of fortresses, as well as caves, military tunnels, which can only be accessed by boat, below we reveal a few interesting places.

Arza and Mamula fortresses

Montenegro is full of fortresses from the Austro-Hungarian period, one of them is Arza - the guardian of the entrance to Boka. Arza is a military fortress from the 19th century on the cape of the same name, at the very entrance to the Bay of Kotor. The color of the sea in that area is extremely beautiful, and it is charming for swimming, diving, photography. Mumula is located near Arza, as both fotresses are at the entrance to the Bay of Kotor. Today Mamula is reconstructed in luxary Hotel, which still can be visited.

Blue Cave

This cave is a real tourist hit, tucked away on the uninhabited part of Lustica Peninsula, with crystal blue color that is created by the reflection of the sun's rays that bounce off its surface during clear days. Blue Cave is one of the most beautiful and largest caves, it has two openings at an angle of 45 degrees, so that smaller boat can enter the cave. A beautiful experience for swimming and diving in the turquoise blue water. There are also 7-10 smaller caves between Mamula and Zanjica that are equally magical and much more peaceful.

Military tunnels from the Yugoslav era

Three tunnels were built in Boka Bay- Rose, Rakite and Spilice - excavated deep in the massifs of Lustica, hidden deep in the rock and almost invisible from the air.
The entrance to the tunnel was covered with fake rocks, mounted on metal panels, to make it look like an ordinary coastal cliff from the air. Only when you get very close from the sea, you will discover a rectangular opening that leads into the mark. Unlike the other tunnels, Rose has a separate truck entrance and vehicle access road on its southwest side, making it a true underground base, not just a hideout. Entrance to the tunnels is by boat, echo effect inside, shade, and perfect for photos, it is an ideal place for a short exploration.