When exploring the expansive London Underground network, one part offers little of interest to the recreational trespasser, that being the DLR (Docklands Light Railway). There are three tunnel sections of note, two involve tunnels under the River Thames, and one tunnel connects Tower Hill to the Bank station terminus. I've covered one DLR tunnel under the Thames here.
This tunnel starts at Mudchute station, where the line dips down to Island Gardens station, before passing under the River Thames. We opted to go very early in the morning before service started, with the intention of seeing how far we could get in ten minutes of running, then spend 20minutes getting back. Being a recreational jogger as well as a trespasser, I gave the others a head start while I got a few extra pics. This is the start of the portal after Mudchute station.

And this is looking at the tracks closing up from within the tunnel, prior to meeting at Mudchute station. Fortunately most of the DLR stations are unmanned, so trips like this are fairly straightforward.

The box like tunnel heading towards Islands Gardens station, just out of shot.

The trip from the portal to Island Gardens station is only a couple of hundred metres, and thankfully the station was quiet and empty.

A portal within a tunnel, the round tunnel that heads down under the River Thames.

A shot looking back towards Island Gardens station. As with all tunnels on the LU network, they're designed to be as annoying as possible to photographers. At least an hour was spent on 'cleaning up' this picture alone.

Thankfully I managed to dodge the green and blue lens flares on this shot, the tunnel at it's lowest point under the River Thames. The track heads uphill towards Cutty Sark station around the corner. Our time limit was up, and it was time to get the hell out of there.

A few minutes of running, and we were back at Island Gardens station. Eagle eyes may spot the 'wired' gates, which presumably sound an alarm somewhere. Unfortunately we didn't spot this on the way in.A few minutes of running, and we were back at Island Gardens station. Eagle eyes may spot the 'wired' gates, which presumably sound an alarm somewhere. Unfortunately we didn't spot this on the way in.

Another few minutes of running, and sure enough, we were back at the portal. No signs of life by the station, only curious looks from an early morning dog walker.

Thanks to Residues and Kev for fast work here.