- my favorite resort on the island is the Mauna Kea resort. You can stay at the Mauna Kea hotel, or the Westin Hapuna Beach hotel, or a vacation rental in the resort. I just stayed in a rental booked through Marriott Homes and Villas (managed by the Mauna Kea Residences) and that gave us full access to both hotels, both beaches, and room charging benefits for all amenities and restaurants at either hotel. Those beaches are the best in the state, IMO.
- snorkeling: there’s actually pretty good snorkeling at the resort beaches. Some other spots would be renting a kayak and snorkeling at Captain Cook monument. 2 step beach at Honaunau Bay is good but crowded. Lapakahi State Park has some great snorkeling and is off the beaten path. Tons of Yellow Tang there.
- hiking: the Pololu valley hike isn’t very hard and is a very pretty black sand beach. Akaka falls is a short hike (small fee to park). Lots of more strenuous hikes if you’re interested.
- you absolutely need a car rental. Everything is at least a 30 minute drive on the island