It's a great area isn't it? I walked over the Merrick a few years ago in winter and had a great day out. On the way back to the car, but still a couple of miles out, my mate stepped into an invisible leg shaped hole and sank up to his crotch in freezing water. After I stopped laughing, I took his pack so that he could leg it back to the car and get his dry gear on.
Cheers, Michael.