Yes, there are fees to pay both in Thailand and Myanmar.
For a Thailand: you will spend days in Surin National Park (Surin islands and Richelieu Rock) and one day in Similan National Park (Koh Bon, Koh Tachai). The total fee to pay is 2000 thb per diver and 1000thb per snorkeler.
For Burma, you will have to pay a combination of visa, border fee and diving fee that must be paid in clean US Dollar Bills at the border.
​Please come with "looking like new", unfolded Dollars bills, it is not possible to change money at the border and while the authorities will accept Thai Bahts, it will be a lot more expensive than paying with USD.