Should I choose University of Hawaii Manoa or Hilo?

Hilo is rainier and has lots more voggy days with the active volcano. If you have any asthma or other breathing issues Manoa would be better. The Big Island has lots of outdoor opportunities for hiking and exploring beautiful places. Manoa is by the city...lots of traffic and busy night life. There are still a lot of outdoor activities on O'ahu...hiking, snorkeling, diving, biking, kayaking...etc. You'll have more interaction with true life international relations in Manoa. Hilo is a sleepy town. The Big Island has a lot more focus on Native Hawaiian culture. From an anthropology standpoint that may be of interest to you.