The manta rays are a must

Rent a kayak at captain cook. Go early and you’ll definitely see lots of dolphins. My favorite thing on the big island

Lots of fun beaches on the Kona side. We like makawalena beach. It’s a hike but worth it.

Honomalino beach is a fun hike and you might have the beach to yourself.

Hike around volcano national park. The hikes are great. Eat at the bowling alley snack bar at the military base. Cheapest food in Hawaii.

Waipio valley is an experience. You must have 4 wheel drive.