What I didn't need was long pants, other than the one pair I wore on the airplane. My policy is to cover all skin when riding in airplanes, to reduce my exposure to other people's bugs, having once gotten scabies from an airplane ride. I only needed one long sleeved sweater, which I wore only once outside of travel days, and I could have lived without the fleece vest. I also did not need the neoprene top, shorts, and paddle jacket that I brought. The ocean is warm. Perhaps if we'd spent a day sea kayaking those items would have been important, but for snorkeling, swimming or surfing for two or less hours, I have enough body fat to keep warm. Also we had hot tubs to get warm in.
I was glad I brought loose, light, short sleeved button down shirts, tanks and shorts and a short skirt. I used all the shoes I brought: hiking shoes, chacos which are also good for hiking, and flip flops for when the chacos were muddy. I was glad I brought shades and a spare pair, even though I didn't need the spares, and sunscreen, and a ball cap. I was glad I brought finger and toe nail clippers. I also used the rain jacket several times, mostly on travel days, because it had good pockets and was warm. A poncho would be better for carrying on outings, though, because it's too hot to wear a jacket and the downpours are short.
I wished that I had gotten a pedicure before I went. I wear sandals year round and the thick dead skin caused trouble when it got water logged. I wished for a better sun and rain hat, more short/sleeveless dresses, and more swimsuit options. Light bike shorts would have come in handy for under dresses. I wish I had brought my own pillow, because at condo #2 the pillows were moldy. I wish I'd brought a better set of carry-on stuff including my own first aid kit with adhesive tape, a music system, pens, stamps, condiments and protein powder for making fruit smoothies into meals.
Phone, chargers (wall, USB)
Wallet, cash, cards, pens
Reading glasses, novel
Toothbrush, dental floss, chapstick
Hair brush, razor
Hoodie, hat, light shell
First aid kit with flexible fabric bandaids, neosporin, tape
Headlamp with fresh batteries
Food bars, supplements including fiber
Water bottle, peppermint tea for flavoring icky water, emergenC
Journal, computer & charger, pencils, stamps, deck of cards
Get a pedicure before going
Spare camera batteries, charger
Shorts, tanks, rash guard / nylon shirt for snorkeling
Swimsuits and short dresses, sarongs
Flip flops, chacos and hiking shoes with treads for mud, socks
Hats, sun shirt (long sleeved)
Shampoo and good conditioner
Coffee, hot sauces, small thermos (cold cocktails on the beach)
Whistle, compass, firestarter all in one
Binoculars for watching surfers and birds