The many cliffs surrounding Sunagakure.

Obviously, one thing is clear. Falling off them would mean certain death.

You can climb around on them quite easily and it's entirely possible to, if you're careful, climb right into Sunagaukare but make one mistake and that's it. You're falling to your death.

It's a good place for bandits to hide out for that reason. Obviously, if you don't want someone hearing your plans or intentions this is the place to be.