I know Maldives is not in SEA and I have been also trying to find a beach and a lagoon like in Maldives in SEA. So far I have not been to do so. It is also the privacy that is attractive in the Maldives. Your beach is your beach and you do not have to share with anyone. The lagoon is so clear and the sand is so white and fine you can walk in the lagoons for a bit in most resorts. Yes the reef protects it too. I have found two in Philippines but there are no resorts there. One is in Ilocos Norte and called Pagudpud and the other one is in Mindanao and is called Mati and there are only day outing beaches.