Borrow some of the digger dogs on here..
Cant remember whose lol..but i remember a pic of a husky or Ni who had dug a proper den in their owners garden ...

Trampolines that are sunk into the ground are very dangerous especially if they dont have a surrounding safety net. You could also possibly get ground collapse round the sides which would decrease the area that can be bounced in plus it would eventually fill with water. FAR too dangerous imoh.

May I ask why? I think trampolines can be dangerous as it is but being sunk into the ground it does reduce the distance you could fall by a few feet. SLB has mentioned that it does have a net, and someone else has mentioned that she'd need proper drainage sorted. I'd probably recommend finding some way of reinforcing the edges of the hole too but is there any other reasons why it would be more dangerous than using it above ground?

Unusual idea! can't imagine anyone stealing a big trampoline, given that it would have to be taken down bit by bit...

If I had the space and wanted to dig a hole that big, I'd make a lovely koi pond. I've always wanted a koi pond but never had a garden big enough to justify putting one in.

Sorry but the title to this really made me laugh What other sort of hole is there but a hollow one

I was thinking the same

Why would sinking it take up less space?

Don't trampolines have wire bits around the sides, holding the bouncy middle? Wouldn't this be very dangerous for anyone walking by and not realising that there was a sunken trampoline?

Well, I think SLB might remember putting a trampoline in her garden and it's going to be quite obvious if the safety nets are up

Yes but when she invites me to a very boozy party, I might forget and feel the need to investigate behind the nets.
Then where will we be?
Yes, yes I know in a hollow hole

It won't be hollow if you're in it

You don't know how true that is

You can get mini-diggers that fit through a normal width doorway/gateway, you know....

Also... what will you do with all that soil??