Hedgehog Friendly Garden?

Here is a pic of my afternoon visitor, which was completely unexpected as, I have lived here for 8 years and not seen a single one. Didn't even think hedgehogs could get in as, as you can see, my garden is completely fenced off. But there is a hole I have discovered under the fence at the bottom of the garden so they have dug their way through.

Now to my question: How can I make my (unruly) garden more hedgehog friendly? There is a pond at the bottom left of it that is home to at least 17 frogs. Is a hedgehog at risk of drowning? Any help/suggestions appreciated.

Denise