[benb]

I've been to Hawaii 3x.. we stayed in Waikiki both times we were on Oahu so didn't need a car every day, but where you're staying you should definitely have one.

Lots of good advice here, but I've done a lot of snorkeling and I would almost put Hanauma Bay as a skip. See if you can find another spot to go instead from a local. Hanauma bay is a very poor example of what Hawaii has to offer for snorkeling, maybe it was good 50 years ago but last time I was there it was pretty heavily damaged due to the ridiculous amount of tourist traffic there. There are all kinds of guys with vans who shuttle people from Waikiki all day long and that amount of traffic just seems to have had a detrimental effect. I don't really have a recommendation for another place on Oahu, I have had more snorkel time on the Big Island and Maui and it was 100x better than Hanauma bay.

You definitely need to take surfing lessons if you're fit and good swimmers (it's a pretty insane workout), also take a drive around the entire island and just stop and stare and take pictures. The north shore is not going to be "epic" in July but definitely drive along and look for the surf spots and hang out and watch. It's much better in the winter.. last time we were on Oahu was in the winter and we got to watch a pro surfing contest at Banzai Pipeline and that was a fantastic way to chill for an afternoon.

I really enjoyed hiking Diamond Head, and Pearl Harbor is so good I spent an entire day there both trips. The Aviation museum at Pearl Harbor is very good on top of the Arizona memorial. There are WW2 vets who still volunteer at the museum. One time I was there I got to walk through the museum with a guy who flew a B-24 in WW2, that is an experience that will not be available much longer! He was amazing to talk to.

The nightlife, shopping, and food in Honolulu is pretty great.. definitely spend time there.

I still haven't bothered to bike in Hawaii.. it is always on my list but there is so much else to do and I tend to get a ton of exercise in the water when I'm there. I was in Kona last winter and heavily debated it.. didn't bring my stuff at the last minute. There is a shop in Waikoloa (right on the Iron man route) which has super nice bikes with Di2 for rent.. but I was going to end up spending several hundred dollars on rental stuff and I hadn't brought my shoes/kit so it wouldn't have been that great. IME that whole Kona coast where Iron Man takes place is a terrible place for a roadie to ride. The Tri guys there seem to have little understanding that bike routes can be/should be fun. I talked to quite a few of them there who just go back and forth up the highway where the Iron Man takes place for their daily rides. It looks like the worst place on the island to ride to me.. not necessarily flat but very straight, no shade, through the Lava field the whole way, and cars going by at 70mph constantly.