Every travel blog tells you to pack sunscreen, wear comfortable shoes, and bring a light jacket. They're not wrong, but they're also not helpful because they're the same advice for Maui, the Big Island, or anywhere else in Hawaii. Pearl Harbor is different enough that you should pack differently, and the stuff that actually matters for a Pearl Harbor tour is basically nothing you'd pack for a beach day.
What You Genuinely Need
Closed-toe shoes are the only non-negotiable item because USS Arizona Memorial doesn't allow sandals or flip-flops on the walkway, and they enforce it. If you show up in sandals, you either turn around and miss the memorial or you buy $40 flip-flops from the gift shop and then feel stupid all day. Bring shoes you've already walked in, because USS Arizona has concrete and metal grating and your feet will hurt if you're breaking in something new. The walk itself is maybe 100 yards total, so you don't need hiking boots, but you do need things you can actually wear.
A shirt with sleeves is required for USS Arizona too because tank tops and sleeveless dresses are not permitted, and this isn't a sun protection thing but rather a respect thing. USS Arizona is a military burial site and the rule exists because the rangers enforce it. If you have kids, pack them a shirt that covers their shoulders and don't plan on changing them later because there are no private changing areas at the memorial.
Sunscreen matters, but not because of the sun exposure time, since Pearl Harbor tours run 4 to 5 hours and you're outside for maybe two of those hours, which isn't long enough to burn if you start at 8 a.m. The sunscreen matters because you're reflecting off water, and the boats run past Ford Island and the channel where the water reflection doubles your exposure. Bring sunscreen you actually like wearing because you'll forget to reapply otherwise.
A small backpack or crossbody bag is better than no bag, but it has to be small enough that you can check it at Pearl Harbor because security is tight and they'll turn you away if your bag is too large or you bring luggage. Most tour operators have a bag size limit of about 11 by 17 inches, so if you're traveling with nothing but a phone and sunglasses, you don't need a bag at all.
What People Pack and Actually Shouldn't
A camera with a big lens sounds like a good idea for memorial photos, but USS Arizona memorial photography is usually disappointing because of the viewing angle and the sun position, and most people take their best photos from the boat ride over rather than from inside the memorial building. Pack a camera if it makes you happy, but understand that the memorial photos won't be the highlight of your album.
Formal clothes are completely unnecessary because some travel blogs suggest dressing nicely for USS Arizona as a sign of respect, but the reality is that hundreds of people visit every day and they're wearing workout clothes and resort casual and whatever else. You don't need to pack a dress or slacks because respectful means covered shoulders and closed-toe shoes, not business casual.
A light jacket is mentioned in every packing list and it's almost never useful because Pearl Harbor is in Honolulu and it's warm year-round, and you're outside for two hours where you won't need extra layers. Unless you're visiting in January or your tour includes a museum with aggressive air conditioning, you won't need a jacket at all. If you're on a boat tour that includes Battleship Missouri or the Aviation Museum, those buildings do have AC, but you can borrow a light layer from someone on tour rather than pack one yourself.
Multiple pairs of shoes is overkill because you're wearing the shoes you're bringing and you're done with it, and you're not changing clothes on a Pearl Harbor tour.
What Actually Changes the Experience
A camera or phone that's actually charged matters more than anything else because low battery means you either rush through or take no photos, which is frustrating, so bring a portable charger if your phone is old.
A reusable water bottle that you can fill in the tour office before boarding helps because you'll be thirsty and tour boats don't always have water available. Bring it empty and fill it once you're on site because security won't let you bring full bottles through the gates.
Sunglasses or a hat might seem cosmetic but they're genuinely useful because the sun reflection off the water is intense and you'll squint through the memorial if you don't protect your eyes. Sunglasses are better than hats because USS Arizona has air-conditioned spots where a hat looks awkward.
A small notebook or waterproof pen matters if you're traveling with kids or if you actually care about the historical details because tours have a 30-minute window at the memorial, and that's enough time to read some plaques and understand what you're looking at, but if you want to remember the details later, writing something down helps. Don't plan on downloading information beforehand because you want to hear it on the tour, not read it on your phone while standing at a war memorial.
What Not to Waste Space On
Don't pack snacks because tour boats don't allow outside food except for babies, and Pearl Harbor has a cafeteria and gift shop with standard prices, and you should bring money for lunch if you're skipping the Battleship Missouri museum or know that most tours include a meal break at a local restaurant.
Don't pack entertainment because your phone exists and that's entertainment enough for four hours, and a tour that runs four hours isn't long enough to get genuinely bored. If you're traveling with a four-year-old who genuinely cannot sit still for tours, reconsider whether a Pearl Harbor tour is the right activity for that child rather than packing tablets and headphones to keep them occupied.
Don't pack beach gear because Pearl Harbor is not a beach activity and you're not swimming or taking a sunset cruise. You're visiting a military memorial and a few museums, so if you want beach time, do that a different day.
The Actual Packing List
Bring closed-toe shoes you've already walked in, a shirt or dress with sleeves, sunscreen, sunglasses or a hat, a small bag under 11 by 17 inches if you want one, a charged phone or camera, a reusable water bottle you can fill on site, and a light layer if you're visiting in winter and museums make you cold. That's the entire list, and everything else is either unnecessary or will be provided on the tour. Pearl Harbor isn't complicated to pack for once you understand what the tour actually involves and what the memorial actually requires.