Looking for more? There are so many competitions out there!
American Regional Biology Competition (ARBC): Check if we have a competition in your region! If not, you can partake in online competition! It's a great opportunity if you want something less advanced than USABO but still above high-school level
International Biology Bowl: Combines an olympiad-like testing format with buzz-in rounds in a tournament-style setup
British Biology Olympiad (BBO): An easier olympiad competition, innit?
HOSA: I don't really know what this is but it's more medicine-oriented.
US Medicine and Disease Olympiad: I never know if this thing actually runs. I've heard mixed reviews.
Science Bowl and Science Olympiad: See if your school has a club or start one!
Not an American? See if your country has its own Biology Olympiad Competition!