Heading to Hawaii soon? Since it is a laid-back place, don’t overthink your wardrobe. You will see most locals in shorts and short sleeve shirts or tank tops.
I recommend packing floral patterns that are breathable for the heat, such as light cotton.
Here is a packing list you can use:
Bathing suits that are comfortable and practical because you will be riding some waves and want it to stay put!
Sun tan lotion
Sunglasses
Sneakers for hiking and outdoor activities
Sandals
Dresses, shorts and tank tops
Jeans for at night (it can get chilly at night in the spring)
Camera
Sweater
A backpack for hiking and carrying all your needs to the beach etc.
Bug spray, again for hiking
GPS if you are renting a car to get around the islands
If you already own snorkel gear, pack that to avoid having to rent them at beaches.
Tip: the hotel beach at the Sheraton on Kaanapali in Maui is amazing for snorkeling and seeing sea turtles.
Kristina Gemella's Travels 
Great list. I would also recommend packing some extra room in your suitcase, as we always seem to bring home more than we started with.