S8 and I rented a sea kayak on the Big Island and had a great time on our own paddling to the place where Captain Cook died from spear cancer. We got to see some spinner dolphins jumping on the way back.
I reckon since I will have 2 kids and possibly GF40 and her daughter that the odd number makes it difficult to find rental of a 3 person kayak - probably need to rent a canoe. Maybe I can rent a sailboat for the ocean.