I just moved out here from Honolulu. There's some bouldering at Waiamea, but this time of year don't do it with anything over 15 foot Hawaiian. The shore break will get yeah.
Additionally, there's a small crag on the North Shore. It's on private land and the locals there have tried to keep it a secret; one grounder and a suit and the things done. It's actually nice rock considering the rottenness of every thing else on the island. Lots of dihedral cracks. Everything is bolted and there's very little trad placements. Also, and I've never seen anything like this, they've got parachute cord on each route leading up through the anchors and back. If you're inclined to TR, you just tie the rope to the end of one of these pieces of string and hoist away. Have fun and Aloha!