On Kona, big island, you can take a local bus for $2, to a state park, where u can rent snorkel equip for $8. Good snorkeling here, many sea turtles and fish. Bus ride is 15 min from where the ship tender lets u off. The ship charges roughly $40 for this trip. In hilo, big island, we rented jeep, thru the ship, and went to volcano nat park by ourselves and to several other places. On maui and Kuwaii, we rented cars thru reps that where at the offload site. We went to grand canyon of hawaii and to the top of volcano haleeakula. Cars are cheaper if you get them thru the car company reps. Call ahead and make a reservation asking them how to do it from where the cruise ship will be. Find another couple on the ship to split the cost. Most people are loking to get around the high prices the cruise line charges.