WWII Tunnel on Brač: Drive the Boat Inside the Rock
A guide to the Yugoslav-era military submarine tunnel on Brač's south coast — what it is, why so few tours visit, what it looks like inside, and the experience of driving a boat into the cavern.
By Marinko (Co-founder & Skipper) · 6 min read · Updated 2026-05-23
What the tunnel is
A military hangar carved into the limestone of Brač's southern coast during the Cold War era, used by the Yugoslav People's Army to hide patrol boats and reportedly small submarines from satellite observation. Built in the 1960s, abandoned in the early 1990s after Croatia's independence.
The tunnel mouth opens directly into the sea — small boats can enter through the entrance and drive several tens of metres inside the cavern. The hangar is unmarked, unprotected, and almost no commercial tour visits.
How it was built
The tunnel was cut from existing sea caves and natural cliff openings, then expanded with explosives and concrete. The interior surfaces are partly carved limestone and partly concrete reinforcement.
Ventilation shafts run vertically through the rock above. The acoustics inside are striking — the boom of the engine echoes for several seconds after you cut it.
The scale is unexpected. Photographs do not prepare you for how large the cavern is.
What it looks like inside
Dim and cool. The sea entrance lights the first 10 to 15 metres; beyond that the cavern is dark. Water inside the tunnel is the same clear Adriatic but takes on a grey-blue tint due to the diffused light.
The walls show concrete reinforcement, rusted metal fittings where mooring lines once attached, and graffiti from various decades.
No facilities. No lights. No tourist infrastructure. It is essentially a sea cave with military history embedded in it.
Why few tours go there
Not on any standard public tour itinerary. The tunnel is unmarked on most maps, requires a knowledgeable skipper to find, and requires a small enough boat to enter the entrance safely.
Larger ferries and bigger tour boats cannot enter at all. Only speedboats and small craft can.
Some local skippers know it from their own boat experience. We include it on our private Brač tour specifically because the experience is genuinely unique and the kind of stop that makes a private day worth booking.
Safety
Conditions need to be calm. Swell at the tunnel entrance closes access — even mild waves make safe entry difficult.
The skipper assesses conditions on the day. We go in if it is safe, we skip and explain why if it is not.
Inside the tunnel, no one swims. The water is dark, the bottom is not visible, and there could be debris from the original military use. You stay in the boat.
Boats inside the tunnel run at very slow speed — idle or just above. The skipper is focused on positioning and turning around.
Photography inside
Challenging. Low light, high contrast (bright entrance, dark interior). A fast lens (f/2.8 or wider) is essential. ISO 1600 to 3200 is normal.
Smartphone photos are possible but limited. The wide-angle is useful for the entrance perspective; the low light defeats most phone cameras for the deep interior.
The boom of the boat's engine reflecting through the cavern is worth a short video capture.
How long inside
Typically 10 to 15 minutes. Enter, drive in carefully, turn around, look at the walls, listen to the acoustics, drive out.
You do not need longer. The novelty is the entry and the scale, not extended exploration.
How it fits the private tour
The WWII tunnel is the first stop on our private Brač day. We leave Split at 09:00, drive south to Brač's south coast, and reach the tunnel by approximately 10:15. The stop is 15 to 20 minutes total including approach and departure.
From there we continue east to Bol and Zlatni Rat, then west to Milna. The tunnel sets the tone for the day — this is not a standard tour, it is the version made by skippers who know the coast.
Other Yugoslav-era military sites
Brač has several more wartime constructions — bunkers, observation posts, smaller storage tunnels. Most are inland and require hiking.
On Vis Island (the larger neighbouring island), there are larger military sites including the famous Tito's Cave used as a partisan command post in WWII. Visiting these requires a Vis Island land tour.
For most travellers, the Brač submarine tunnel is the most accessible and dramatic Yugoslav-era military site in the Split area.
Further reading: see also our Bol town 90-minute plan, the Zlatni Rat beach guide, the Milna baroque-harbour read, and the broader Hvar-vs-Brac comparison. Book the private Brac day at /tours/golden-horn-bol-private-tour.
Ready to plan the route?
Compare group and private speedboat tours from Split, or go directly to the route mentioned in this guide.
About the author
Marinko
Co-founder & Skipper · 20 seasons in Split
Co-founder and one of the two captains who built Navy Blue Yachting from a single boat. Over 20 years on the Adriatic and a lifelong passionate fisherman — he reads sea conditions the way most people read a weather app. If you are on a flagship Blue Cave day in shoulder season, he is most likely the captain.
Meet the rest of the crew →