Well plenty of great diving spots in Thailand, but in the countryes around also do have superb places, so this first proposal

Pandan Island

Pandan is a small Island near Mindoro Occidental, just south of Manila, not to far, many ways to reach the place even by seaplane landing you in the critalline waters off the beach of Pandan...

This place is run by Dominique a French men for over 20 years now, the dives are famous around the Island with the company of Giant Stingrays ( nobody died of stingray hit there yet...)

Well check the website if interested, great place...