Ah - so it's a sewer!
The reason I asked is that we were walking round there back in the 90s and saw a group of lads near the end of the pipe. One had actually got onto it, sitting with legs straddled , and shuffling across on his btm.
I was horrified, but daren't shout to stop him as he might have fallen off

Also I thought the pipe didn't look very strong and could have broken. We were talking about it the other day, saying how kids love to do dangerous things. As we did when young, but never ventured on there!
To the previous poster - thanks for the interesting website.
Another favourite haunt in Seaton Sluice was Holywell Dean and Starlight Castle, but that's a story in itself, lots of history there.