Jan van Egmond
Google
Gorgeous scenery, it's a unique experience. Take a good tour guide like Jungle Hut and bring long and short clothing, plus a raincoat for when you're on the longboat (more for the waves, less for the rain). You can go kayaking for free from your bungalow as well.
Down at the Park HQ, you can also do 2-3 hours walks / light treks on your own, and if you want to go longer, you must book a guide separately through your hostel. It's a breathtaking little walkabout, with places to swim and, if you're patient, ample wildlife to be spotted.