we booked a quad biking trip through mr sings beach bar on the front by the evason hotel, the local guides were really good. they took us past the pineapple plantaion, mangrover forest park and onto the local beach and all around the local town.
The resort we were at offered to hire one of the local fishermen to motor us around in his boat for the afternoon. The price was reasonable, and they promised we'd see monkeys, so we signed up. If you stay at any of the beach-side resorts near Pran Buri (but the Anchana for sure), you can probably get the same deal. It was great, maybe the best part of our Thailand trip. We clamboured onto his rickety fishing boat, and he nimbly hopped on. Our first stop across the way was an island populated only by monkeys, who it seems survive off the food offerings of tourists. He grounded the boat and we hopped off with a bunch of bananas. Those little guys were really bold! So funny! Anyways, apart from a couple of island shrines, he took us to a mountain trail that led to the most amazing caves I have ever seen. We kept delving deeper and deeper into the mountain, and the caves kept getting bigger and bigger. Most of the time they were lit from holes in the roof, whence water dripped to feed the plants within. Miraculous. In the biggest chamber a Buddhist temple had been built. What a spiritual place. You've got to see it.
This is a lovely national park that stretches along the coast. There are birdwatching wetlands, caves, temples, very open natural area.