The Divemaster and I did the Big Island and Oahu. He is a seasoned Hawaii man with more than a dozen visits under his belt, so he knows from the islands.
If you’re a diver like we are, the diving is better on the Kona side of the Big Island as previously mentioned, but I was less than impressed. I found the viz very poor overall (I’ll go back to the lower Bahamas for the best diving, methinks). You’re probably better off snorkeling, now that I think about it. And yes, the Mantas are awesome. I just missed a chance to swim with a whale shark, which is one of the few things on my bucket list.
We did Volcanoes National Park, which might not be your thing. With the recent upsurge in eruptions out there, I don’t know if the park is open to visitors at the moment. Easy enough for you to find out.
That said, let me stress that the place is Rugged with a capital R because of the unevenness of the lava fields. We were well prepared, given his previous visits, and it was still a serious workout for both of us. You can and will walk miles of it.
If you decide to walk it – provided it’s even open – wear sturdy hiking shoes or boots (I totally destroyed my New Balance sneakers. I threw them in the trash after we got back to the hotel room. The lava had ripped them to shreds), take plenty of water, a powerful flashlight with extra batteries, extra clothing (it cools off considerably after dark out there) and some lightweight snacks.
The Hawaii Parks Dept. clearly indicates with signs everywhere, you are on your own after dark and after you’ve walked out a certain distance, so take that into consideration. People can and have died out there.
Despite how it sounds, the visit is totally worth it. There is absolutely no light pollution anywhere. The eruption at night is **amazing **and the star field above your head has to be seen to be believed. It was my favorite thing out of all the stuff we did in Hawaii.
Oh, and please Do Not take any of Pele’s Children (pieces of lava or really, anything found on the lava fields no matter how interesting it looks) out of the park or out of the state. The Hawaiian Goddess of Fire will not be best pleased and you will come to regret it. Better a happy goddess than a pissed-off one to ruin your vacation.
If anything, leave an offering behind TO Pele before you leave the islands.
On Oahu, I highly recommend Pearl City and Pearl Harbor where the Arizona Memorial, the Mighty Mo (Missouri) and the Bowfin (sub) are on display. Well worth the tours. Waikiki is fun, if touristy, but the Royal Hawaiian Hotel is worth a walk-through. Some serious history, there.
The National Memorial Cemetery of the Pacific (Punchbowl Crater) is also worth a walk-through. We didn’t get to the Palace, which I’d have liked to have seen.