Hawaii is casual: sandals, bathing suits, and comfortable, informal clothing are the norm. In summer, synthetic slacks and shirts, although easy to care for, can be uncomfortably warm. Only a few upscale restaurants require a jacket for dinner. The aloha shirt is accepted dress in Hawaii for business and most social occasions. Shorts are standard daytime attire, along with a T-shirt or polo shirt. There's no need to buy expensive sandals on the mainland—here you can get flip-flops for a couple of dollars and off-brand sandals for $20. Golfers should remember that many courses have dress codes requiring a collared shirt. If you're not prepared, you can pick up appropriate clothing at resort pro shops. If you're visiting in winter or planning to visit a high-altitude area, bring a sweater or light- to medium-weight jacket. A polar fleece pullover is ideal.
One of the most important things to tuck into your suitcase is sunscreen. Hats and sunglasses offer important sun protection, too. All major hotels in Hawaii provide beach towels.
You might also want to pack a light raincoat or folding umbrella, as morning rain showers are not uncommon. And on each of the island's windward coasts, it can be rainy, especially during the winter months. If you're planning on doing any exploration in rain forests or national parks, bring along a sturdy pair of hiking boots.