I'm a wine professional, living in Bangkok and travelling frequently throughout South East Asia. I'm a huge fan of Laos and Cambodia and off the beaten track travel. Feel free to contact me at: www.facebook.com/mil.elephants
There used to be just one crab shack, now there are four or more. Why? The Crab Shack (original version) offers amazing fresh crab and seafood fished straight out of the sea in front of your eyes and cooked with terrific local herbs and spices including Kampot Pepper. The signature dish is of course crab: pepper crab.
Tables are set up on the sand among the trees just at the water's edge, along the coast of the Gulf of Thailand at Khao Ya Beach which is about 6 kilometres from the centre of town. The easiest way to reach the Crab Shack is by hiring a tuk tuk driver to take you there. Make a day of it, and get someone else to do the driving. Depending on how long you go for it'll cost between $10 and $20 for transport.
The sea is very calm and shallow at Khao Ya beach so you certainly won't be doing any surfing, but it's a great place to hang out (literally in one of the hammocks strung up between the trees). Unlike many beaches in Asia and Cambodia there are no beach sellers, no little irritations, other than the odd sand fly.
Back to the food, the menu is limited to,pepper crab, or whatever fresh fish has been caught that day. They also do grilled pork loin which is delicious, but who comes to the beach to eat pork? Not me.
When your crab comes they'll bring you a big bowl of water and lime to rinse your hands, so don't drink it. This really is hands on food. Drinks are limited to water, soft drinks and beer. They provide you with big buckets of ice for drinks because it does get very hot here.
All the shacks along the beach are called "The Crab Shack" so how will you know that you're at the right one? Make sure your driver turns left when you reach the beach. The original shack will be the first one you see on your right. It's the most well established one and easy to pick out.
The staff speak very little English, but are lovely and friendly. The menu is basic, so any variation on their limited offering might be difficult to communicate. Generally prices for crab and fish are charged at market price, but they are honest.
I generally head there for the day, take a book, or something to do and enjoy the peace and quite and the amazing food.