omg i just had a bit of an experience. I accidentally took a wrong turn on my bike this afternoon and ended up in the Rotherhithe Tunnel. Not one of my finest moments, and I must admit I was in a bit of a state when I got out the other end. I'd never been in the tunnel before so didn't really appreciate how long it was or how narrow the lanes were. Not only that the air was so hot, humid and stale it was hard to breathe.

For those unfamiliar with the tunnel, it goes under the Thames, connecting the north and south banks of the river. According to Wikipedia, it's 14.5 meters below the high-water level of the river and about 1.5km long. Apparently it's the 10th most dangerous tunnel in all of Europe. Some parts are quite windy and the lanes are only about 2.5 metres wide, making it impossible to overtake, so I was holding up traffic big time. The speed limit was 30km/hr, but I was going that fast, if not faster out of sheer panic. Yikes! Also, the ventilation's so bad in there there are signs instructing cars to turn off their engines if stationary. So basically, I couldn't breathe, had sweat pouring down my face, cars roaring up my arse and on top of all things i was running late. The worst however, was when I got out the other end and realised that I needed to turn around and go back through it, otherwise I'd have to ride a VERY roundabout way to find a bridge to get back across the river to where I'd taken the wrong turn in the first place. Not pleasant at all!!! After I'd gone through for the second time I had to get off my bike for about 5 mins to compose myself. Far out! never doing that again.

Here are a few pics (no i didn't stop and take them - i'm not that crazy, they're from Wikipedia)...

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check out how narrow the lanes are. that's one lane for each direction.

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more about the tunnel can be found here:
http://en.wikipedia.org/wiki/A101_road