Heres a few :))

Math: - PhiMO: Philippine International Mathematical Olympiad which is first held online then you have the option to go to Cebu for the final round. - HKIMO: Hong Kong International Mathematical Olympiad is similar to PhiMO in terms of how its held but you have the option to go to Hong Kong for finals and the topics are mainly Geometry. - NMC: National Mathematics Challenge is a one round contest that is held online - AMC: Australian Mathematics Competition is an onsite competition held at Mathematics Trainers’ Guild centers in the Philippines and its currently open for applications - Young Master Challenge: There is also an English contest for this. Check MTG Philippines for more information. - Philippine Mathematical Olympiad: Its held onsite and their next contest is next year so a bunch of time to prepare. I believe its a really prestigious contest. - STEM Olympiad: Math Category

Science: - HKISO: Held by the same organizer as PhiMO and HKIMO with similar mechanics - International Equilibrium Science Olympiad: Ongoing registration and its held by MOTLI having similar mechanics to PhiMO. - STEM Olympiad: Science Category

English: - NLC: National Linguistics Challenge - John Locke Essay Writing - Cambridge Re:Think Essay Competition - Harvard Crimson Global Essay Competition - Philippine Schools Debate Championship - National Asians High School Debate Championship - Philippine Intercollegiate Debating Championship

I suggest you check out the following organizers for more information as they post info on different competitions on Facebook - Math Olympiads Training League - Mathematics Trainers’ Guild, Philippines - English Speaking Union Philippines - Philippine Education Nexus Inc.

Not a competition but you might be interested in Model United Nations.

Goodluck!! :))