i know that this place is not outdoor and probably not a usual tourist site. but if you're an entrepreneur and you need a place to consolidate or merely a place to meet other people who has the same passion as you do, than Protohub Honolulu is the perfect place for you! even if you want to do an event and have a hard time finding a place, you can book it here.
Protohub Honolulu is a co working space that specializes in events and programs that foster a supportive community, develop professional network, connect investors and entrepreneurs, provide entrepreneurial training, and implement funding/investment programs. for more info on this amazing space, check out their website: http://www.protohubhonolulu.net/en/about
with amazing decorations and comfy couches, i wouldn't mind staying long for brainstorming with a cup of hot coffee ;)