Khanom's Pink Dolphins are very rare animals indeed. Very shy, unless you have some fresh fish in your bag of tricks.
You can book an excursion from the reception point at Leeloo Cabana.
The trip costs 1,000THB per person, and included in the price is transfer there and back, and a tour of the pop up limestone islands all around the bays near to Don Sak. The trip starts 7:30AM and you will be back at your resort by 1PM.