Casiguran Sound is located in Casiguran, Aurora, Philippines.

Casiguran Sound is a bay nearly enclosed by the Casiguran landmass and the cape of San Ildefonso. Only a kilometer-wide inlet serves to connect the sound to the sea. Its very location provides protection from the typhoons that seasonally ravage most of the province. Casiguran Sound is also unaffected by the monsoon winds that blow from October through February, making it an ideal spot for windsurfing, should facilities be available. For the time being, bring your own windsurfing equipment. The area has its share of white beaches and numerous places for relaxation. Many foreigners have taken advantage of the natural placidity, having built vacation homes along the coast.

Source:

Aurora.ph