I was out looking for drains and happened to see a small bridge over a creek that was divided up into three channels. Strangely while there were three channels going underneath from the upstream end there were four channels coming out!

I took out my torch and shuffled up the low drain that formed the fourth exit. It went sideways away from the bridge for a long way - just a low concrete box - until it joined some other pipes at a small room. Unfortuntately it got lower there and full of water so I could'nt go any further. I ended up going back the way I came and playing around in the bridge channels for a while

When I work out how to take photos in drains I will go back!