Deep inside a forgotten Undersea Tunnel

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The Lost Trails

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Hidden beneath the waves in this small coastal town lies a forgotten undersea tunnel. It was build in the 70s, a time when Yugoslavia was rapidly developing its industry, which had an absolute priority. All resources were relentlessly exploited for industrialization regardless of cost. This town was no exception, so because it already had a bulk carrier unload facility present, it was chosen as the location of a new coke production plant. As the new factory location was right opposite the existing ship unloading facility, a 400 m long undersea tunnel was constructed connecting the two. Using a long conveyor belt, coal was unloaded from the big transport ships and transferred to the coke factory. But why didn't they build a bridge or gone around the bay, you might ask? The answer is simple, aesthetics. A bridge would interfere with shipping and take away from the bay's beautiful landscape.







The tunnel consists of individual pipes 40 m in length that were made on land and then loaded on a transport ship before being submerged and connected underwater. To not obstruct normal shipping operations, the tunnel was laid on pillows 6 m under the surface.







The cookery, with it's 250 m tall chimney began production in 1978. But after 16 years, and more than 13 million tons of produced coke, the plant was shut down due to high pollution and the tunnel left forgotten. Locals complained that the water around the plat smelled, and it would frequently change color (dark red).

Because of space constraints and steep cliffside, the train terminal for handling the finished coke was build on a cliff above the plant. This arouses a new problem, how to get the coke uphill to this new terminal? So, hey dug up another tunnel, this time a 750 m long one, which housed the rope way for transferring the coke uphill. All along the tunnel were piles and piles of finished coke left there after the plants closure.



We have been in many abandoned tunnels/bunkers in the past, but this one was one of the creepiest explorations to date. You get a strange vibe walking deep in a tunnel like this and seeing only darkness in the distance as you hear your every footstep.

There is a lot of thing we didn't get a chance to photograph, as our main objective was to film the exploration. If you are interested in the full history and footage, you can check out the full exploration:

 

Foxylady

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That's really interesting to see and well done for braving going in there. We had a similar temporary one in my seaside town, but that was much smaller in order to bring in grit and sand from ships out in the bay to build up a flood plain, but it's great to see such a permanent, walkable one. Good stuff! :)
 

Hayman

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Both tunnels well-videoed - and I was getting the same feelings the two chaps were getting! A bridge instead of the 'undersea' tunnel would probably have ben a very functional structure; perhaps left unbuilt. Wot no local 'Sustrans' to make it into a cycleway?! With both ends fitted with grilles, not closed doors, I expect the air blows through the concrete tubes quite easily. The small amount of rust and no vegetation growth suggest a dry atmosphere. I'm not sure what the 'dripping' mught have been; no obvious water ingress. Thanks again.
 

The Lost Trails

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@Hayman We thought the same, but there was zero wind through the tunnel when we were there. The "dripping" sounds are still a mystery. There are supposedly huge ballasts anchored on the tunnel outside to keep it stable, maybe as they move it creates the drippings sounds inside.

@Roderick Yeah, it's difficult to "reproduce" the felt scariness in a video, but man when we were near that spider in the second tunnel, it wasn't very comfortable.
 

Hayman

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@Hayman We thought the same, but there was zero wind through the tunnel when we were there. The "dripping" sounds are still a mystery. There are supposedly huge ballasts anchored on the tunnel outside to keep it stable, maybe as they move it creates the drippings sounds inside.

@Roderick Yeah, it's difficult to "reproduce" the felt scariness in a video, but man when we were near that spider in the second tunnel, it wasn't very comfortable.
Thanks for your reply. I realise that the quite sharp angles where the level sections of the tunnel meet those of the approaches from well above sea level would restrrict air flow to a great extent - but that the interior is largely clear of any vegetative growth suggests a dry atmosphere brought about by wind removing any potential dampness. Which is the reverse of the 'dripping sounds'. You said only sounds - not any sight of dripping. Noises from the movement of the huge ballasts reminds me of the undersea tin mine tunnels in Cornwall. A miner who worked the Geevor mine told me of how he could hear the sea bed stones above him moving with the currents of the tide.

The presence of rubbish in the trough left from the removal of the conveyor is another question. Probably - as was suggested - the result of rain water washing it in from outside - or from near - one or other or both of the entrances. What was what looked like a car tyre doing there?
 

The Lost Trails

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@Hayman We specifically looked for any sign of water ingest, didn't find any. But it's also expected because any small hole would result in the tunnel flooding until the water levels out.

Noises from the movement of the huge ballasts reminds me of the undersea tin mine tunnels in Cornwall. A miner who worked the Geevor mine told me of how he could hear the sea bed stones above him moving with the currents of the tide.
Interesting, didn't know that you can hear it so clearly. Maybe it were the sea bed stones after all. Because the tunnel was build on tall pillars, you can presumably hear all sorts of sounds coming from undersea.

The car tire was probably thrown in just like the other trash, but compared to the other garbage washed down by rainwater, I think it was rolled down by someone through the entrance. As the tunnel is straight, it ended up in the center.
 

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