I knew that we do already have a time zone for Philippines, Asia/Manila called "Philippine Standard Time" with an offset of UTC+8:00 but the other one I was requesting is for the body of water surrounded inside the mainland such as the Ocean or Sea.

I'm proposing to add UTC/GMT+8:15 to your database We do have an 8:30 and 8:45 zone. Why not 8:15?

Plus,and if there's an specific location it's Asia/Philippines with different abbreviation "Philippine Pacific Time" with offset of UTC+8;15and will be used inside Philippine sea (not in mainland)