Besides being a great beach for swimming and shells, this is THE place to see the dolphins work together to push their dinner up on the banks of the inlet to the Kiawah river.
When you get down to the beach, turn right and walk a mile or so until you get to the river inlet. Anywhere from the head of the inlet to several hundred yards up shore is a good place to wait and watch. Then, as if on queue, right before low tide, the dolphins appear. I've heard it can be hit or miss, but we were lucky enough to see two dolphins.
The problem we ran into is that on the other shore, where the dolphins were, there were a bunch of people too dumb to realize that standing right at the shoreline and following the dolphins deters them from doing their thing. When the smart dolphins manage to move away from the dumb people, they work together to push fish up on the shore and grab them. It's pretty neat.
So by all means go see the dolphins, but please be respectful enough to hang back from the shoreline 50 yards or so - you'll get a much better show!!
Hint: Take water and sunscreen. It can be a long hike for young kids under 8 or so. A large wheeled stroller or bikes with kid carriers would work well if you have little kids.