There are two main beaches in KSRY. If I am correct DD's pics, or rather the pics attached to DD's post, (happy now MtD?) are of the larger of the two beaches, usually called Dolphin Bay.
The beach is about a Km long with a road running the full length of the beach above high water mark. On the other side of the road mostly in the centre of the beach are a few small resort type places.
Here's a link to one of them http://www.dolphinbayresort.com/
I believe it's for sale if anyone has a few million spare.
Other than the resorts there are a few restaurants where you can buy the usual selection of Thai dishes, sea food as you would expect is fresh and fairly cheap.
The beach itself does not seem to get much use and as it is in a partialy enclosed bay does not get the same regular cleaning by the tides that more exposed beaches do. This means that when the tide is out and you want to swim, you will have to walk through about a 100m of ankle deep sticky mud before you reach deep enough water.
Apart from swimming eating and laying around the only other attraction I found was to hire a longtail and take the trip round the bay tour to admire the outlying islands and possibly spot the dolphins from which the bay gets it's name. Oh! of course the resort is a good place to explore the park from.
I am told it gets more busy at weekends but the day that I was there our family were the only ones on the entire beach.