Tunnels/tubing big enough to crawl through?

[Frimley111R]

We fit a lot of wooden climbing frame systems and have had a request for a tunnel for kids (actually adults in this case) to crawl through. This is the first request we have had for this. I can't help thinking that their are lots of industrial pipes that we could use for this but I am at a bit of a loss where to start to look. The pipes ideally should be plastic but other materials may be ok.

Any ideas?

[Frimley111R]

Yep, waterslide ones are ok but probably quite expensive when compared to a piece of 'industrial' type pipe. It only has to sit on the gorund and then we can secure/support it to stop it rolling around, or even bury it/cover it, not sure yet.

[Frimley111R]

I am not sure' it'd be rigid enough although potentially it could be a semi circle on the ground (although a bit muddy1)