Make a list and start early, but don't worry too much. Most places in Hawaii have Walmarts and Kmarts and Longs Drugs and ABC stores in case you forget something. Prices are a little higher in Hawaii, but the difference for sundries will be negligible, usually.

• Swimsuit
• Sun protection you can wear like comfortable hats, sun shirts, visors, and full-body suits for the kids. Hawaii is closer to the equator than anywhere else in the continental U.S. and the sun is more intense here. Plus, you'll be out in the sun so much more. Even a small sunburn is uncomfortable and will put a crimp in your vacation.
• sunglasses
• sunblock, at least SPF 30. I put spf 50 on my son until he was 3.
• comfortable walking shoes - if you want to do any sightseeing you will need to walk. I advise tennis shoes or even hiking boots if you are used to them.
• slippers (flip-flops) or sandals
• Water safes (you know those little waterproof containers you can wear around your neck or put in a swimsuit pocket for money and room keys at the beach. You can buy them once you get here if need be.
• Light, easy-wearing warm weather clothes like t-shirts, tank tops, and shorts
• light sleeping wear
• if you will be staying at elevation or visiting the top of any of the mountains bring a sweater or sweatshirt. It does get cool, especially in the evenings, above 2500 feet elevation.
• Tupperware or ziplocks - for bringing small snacks to the beach and on the road with you
• travel mugs - for taking your coffee on the road with you
• fingernail clippers
• earplugs
• beach towels (only fancy, contained hotels will provide them) - consider buying these in Hawaii for an instant souvenir
• snorkel and mask and fins if you own, otherwise buy, borrow, or rent them here
• camera and film (if you still use it)
• An extra piece of luggage for everything you acquire while you are here
• medications, prescription and common over the counter that you take often like motrin or antacid
• personal identification, drivers license
  for Kids
• umbrella stroller - even for young children who don't use them much at home, you'll be happy for it in Hawaii, kids seem to have a lot more grabby meltdowns on vacation
• swim diapers
• decongestants and pain relievers if you use them. My son always seems to catch a cold when we are on vacation.

Carry-on tips
When we travel, my husband and I always include one full change of clothes and a swimsuit for all of us in our carryons. That way, if our luggage is lost or delayed we can still go straight to the beach or pool after a long flight if we want to.

Money or traveler's checks
If you are from the continental united states, your atm cards and credit cards will work here. Don't bother with extra cash or traveler's checks.

Unless you are planning on going somewhere very fancy, don't bother with the formal wear. You just don't need it here. Clothing is very casual - business wear in all but the most formal places is an aloha shirt with slacks or even mu'u mu'us (moo-moo) (light shapeless dresses). Even the government and the television news anchorpersons wear Alohawear (light clothing with bright hawaiian prints). For an online preview of Alohawear, see HiloHattie. Don't buy before you come, make the shopping part of your Hawaiian experience! (unless you really want to) You should bring comfortable shoes (tennis shoes for me) for all the sight seeing. You will be walking around.

If you are planning on hiking or other specialty sports, bring the small equipment - like hiking boots and backpacks. It will be a little more expensive to buy here. When packing, remember to save a little space for items acquired on your trip. If you do find yourself with too much on the way back, go to the post office and mail it or the rest of your clothes home.