Did a trip to the Mergui Archipelago (Burma) about two years ago, there are 800 islands, many uninhabited and some the size of Singapore. Crystal clear water, white sandy beaches, undeveloped tropical paradise, if the Junta ever get their fingers out and open up tourism there Thailand can kiss its tourist revenue goodbye.
A little closer to home though:
Koh Talu: great little island only two hours away, clear water, coral reefs, great beaches. The only drawback is one resort has the monopoly on island accommodation so you need to pay through the nose or do day trips:
http://www.bangsaphanguide.com/bangsaph ... ctions.htm
A beach on Koh Talu ... anyone seen my horse ... come to think of it where is the hotel?
Chumphon: just three hours from Hua Hin and the water gets even clearer, Tung Wa Laen beach at Chumphon is a great little spot, also with offshore islands for snorkelers and divers:
Chumphon beaches are currently tourist free ... well apart from long weekends when Bangkok moves there.
Pretty much all of the beaches on the Andaman side beat HH and Pattaya in terms of water quality and cleanliness, ones that stand out for me are at Khao Lak, Koh Lanta and the islands in Trang province.