digging in the runaround :)

Last weekend, we managed to assemble one length of Runaround mesh tunnel, which is now fixed to Tulip & Mango's run via a Runaround pipe and they can access it at all times. It'll be extended this weekend but that was as far as we had got.

For some reason, even when we open the end up so they can get into the garden, they are both obsessed with digging inside the tunnel!
They've never bothered digging anywhere else, but they'll happily sit in there digging away. They are down to the under-mesh now. I think having the Runaround on grass might have been a bit optimistic. Contemplating digging out a shallow trench under it now and filling it with sand on top of the mesh so they can dig to their hearts' content. Any other ideas?

Could you create a dig box instead and half bury some tunnels in there?

Hi Fifibutton! I suggested that kind of thing to OH but he was determined to give the turf a try. The tunnel is now 12 feet long, and has been dug down to the mesh in several places lol. Problem is now it's in, we can't really get in to do much about it! I think we may end up just putting gravel down in it at some point. Silly buns.