So there's this old Shetland pony at my barn who ALWAYS gets out of her pen. They honestly have to keep her in a big corral with panel fences to prevent her from escaping. (and I know what you're thinking, 'bad fencing', but honest to goodness, it's as good as anybody else's fencing out there, it's wooden with an electric wire out in front of it to prevent them from trying to jump or do soemthing to it.)
So they thought they'd let her out to pasture with the other ponies for once, because she was getting lonely and bored in her pen.
One day when me and my friend (who's also the barn owner's daughter) were doing stuff with our horses, when she yelled "Cocoa's out!" .. So we freaked out and tied our horses up (tack still on) and went to go follow her, but she was off and running and not looking back.. We called the her dad, while we were running, but finally Cocoa was out of sight and we were freaking out because she was probably down on the highway which isn't too far from the farm...
So we ran down to where we thought she went (we should be olympic runners, that's how fast we ran that mile down to the highway :P) and we saw her running on the other side of the highway (on the gravel road on the other side of the hwy) thinking nothing happened, but then we saw this CAR pulled over to the side of the road with a dent on his bumper.. He gets out (turns out to be a kid we know from school) and says "are you looking for a pony" and we said yes, and he said "I tried to stop but I just hit one on the road but it got up and kept runnin'" and we looked at each other like ... and said ok and ran accross the highway where we saw Cocoa in the ditch, just eating grass, so we went up to her, and she tried to run away again, so we just gave up and waited for my friend's dad to get there.
He ended up catching her somehow and took her to the vet thinking she was going to die or something. (my friend and I were completely bawling)
Here's the kicker: SHE WAS COMPLETELY FINE. Only a big bruise where she was struck (shoulder/ribcage area) and a little road rash where she fell, but other than that she was completely fine.
So we went back, checked the fence, and there was no way she could've gotten out other than JUMPING it. And this is a 9hh Shetland Pony we're talking about.
So that's my reason why I think Shetland ponies are the toughest ponies out there.