Oahu

Waikiki’s longest-running catamaran, sailing since 1977 and launching straight off the sand in front of Duke’s, between the Royal Hawaiian and the Outrigger Waikiki. The day sail is a single hour out toward Diamond Head and back under sail, which is about the right length for small children and costs less than most Hawaii activities. There is no minimum age and boarding is a walk down the beach rather than a harbor check-in, so it works as a spur-of-the-moment outing on a beach day. This is the cheapest way to get a family onto a sailboat in Hawaii.

A 44-foot catamaran that launches off the sand behind the Sheraton Waikiki and sails the water directly in front of Waikiki with Diamond Head off the stern. The operator’s own description is that the wind and waves are the engine, and it has a reputation among Waikiki boats for actually hoisting sail. The 11am and 1pm Tradewind sails are the family slot and the cheapest; the later afternoon and sunset departures are built around an open bar and cost more. Children under 3 sail free and there is a child rate through age 12.

The battleship where Japan formally surrendered in 1945, moored on Ford Island and open to walk through from the teak deck down into the ships interior. Kids stand on the surrender deck, sit in the wardroom, climb up to the bridge and look down the sixteen-inch gun barrels. Guided tours go below into crew quarters and the engine spaces. Large parts are enclosed which makes it workable in rain, though the main deck is open. Reached by the Ford Island shuttle from the Pearl Harbor visitor center.

The state museum of Hawaiian history and natural science, and the first thing to reach for when a beach day on Oahu gets rained out. Hawaiian Hall is three koa-wood galleries of chiefly regalia, feather capes and a whale hanging from the ceiling. The Science Adventure Center has a walk-through volcano with a lava-flow demonstration that erupts on a schedule and genuinely startles kids. There is a planetarium running Polynesian wayfinding shows about how navigators crossed the Pacific by stars. Plan three hours and check the daily schedule of hula and science demonstrations on arrival.

Oahus childrens museum in Kakaako, with four themed galleries built for hands-on play rather than looking. Kids run a mini television studio, work in a pretend supermarket and fire station, and explore Fantastic You where they walk through an oversized model of the human body. Rainbow World covers cultures across the Pacific with costumes and homes kids can go inside. It is aimed squarely at the under-tens and is the best wet-weather option on the island for that age. Two to three hours and a short drive from Waikiki.

Free admission, air conditioning and contemporary Hawaii art in a historic Spanish Mission style building downtown, which is a good combination on a wet Honolulu afternoon. The collection is entirely by artists connected to Hawaii and skews colourful and accessible rather than difficult. There is a dedicated hands-on family gallery where kids can make art and use activity kits. Because it is free you can walk in for twenty minutes and leave without guilt. Sculpture garden outside for when the rain lets up.

A city and county botanical garden on Oahu that allows weekend tent camping in grassy lawns beneath the sheer green wall of the Koolau Range. It is one of the only genuinely quiet, non-beach camping options on the island, and the setting is spectacular: 400 acres of themed tropical plantings, a small lake for catch-and-release fishing, and the ridge rising straight up behind the tents. Camping is limited to a Friday through Monday window and requires a permit obtained in advance from the county.

A beautiful low-slung museum built around a series of open courtyards, which makes it feel airy rather than institutional even in the rain. The Asian art collection is one of the strongest in the country and the Japanese and Chinese galleries have armour, screens and ceramics that kids react to immediately. Family art activities run on select weekends and children are admitted free. The cafe in the courtyard is genuinely good, which matters when you are killing a wet afternoon. An hour and a half is plenty with kids.

The only royal palace on American soil, home of Hawaiis last monarchs and a genuinely moving place to bring older kids. Guided and audio tours take you through the throne room, the grand staircase and the upstairs room where Queen Liliuokalani was imprisoned after the overthrow. The palace had electric light and telephones before the White House did, which is the detail kids remember. Everyone wears booties over their shoes to protect the koa floors. Tours run on a schedule so book ahead, and note it is not a place for restless toddlers.

The internet’s version of the North Shore day trip is: drive up, take a picture at a beach, buy shave ice, drive back. Four hours of highway for one photo. Here’s a better version. Run the island clockwise - Kailua first, North Shore last - and everything lands at the right time. The water at Kailua is calmest in the morning. The Koolau mountains behind Byodo-In and Ho’omaluhia are only clear of cloud early. The green sea turtles at Laniakea don’t reliably haul out until afternoon. Go counterclockwise, like most people do, and you miss all three. ...

Two working seaplane hangars on Ford Island that still carry bullet holes from December 7, 1941, filled with restored aircraft from that day forward. Kids see a Japanese Zero, a B-25 bomber and Cold War jets up close, plus a restoration shop where volunteers work on planes in view. Flight simulators let older kids fly a mission and are usually an extra ticket. The setting does most of the work here because you are standing inside the actual buildings. Reached by shuttle bus from the Pearl Harbor visitor center.

A real World War II submarine you go down inside and walk through end to end, which is the kind of thing kids talk about for years. The passages are genuinely tight, the bunks are stacked beside torpedoes, and an audio tour explains what life aboard was actually like. An adjoining indoor museum holds torpedoes, a Poseidon missile and submarine artifacts. It is at the Pearl Harbor visitor center so it slots in alongside the memorial and aviation museum. Not suitable for strollers and small kids need to manage steep ladders.

A small aquarium right on the Waikiki shoreline focused entirely on Pacific and Hawaiian reef life, which means kids see the same fish they might snorkel with an hour later. Hawaiian monk seals live in an outdoor habitat and are the highlight for most children. There is a giant clam collection, a jellyfish gallery and a shallow outdoor touch tank. The whole visit runs about an hour and it is walkable from most Waikiki hotels, which makes it an easy rainy-morning pivot. Partly open air, so a poncho helps in a real downpour.

A 4.8-mile loop trail through a forest of eucalyptus, Norfolk pines, and native plants with views of Pearl Harbor and the south shore. The trail is mostly shaded which makes it one of the more comfortable hikes on Oahu even on warm days. Kids enjoy the variety of terrain and the WWII airplane wreckage along the trail adds historical interest. The loop format means no backtracking. The trailhead is inside Keaiwa Heiau State Recreation Area which has picnic areas and a campground for extending the visit.

A stunning replica of a 950-year-old Japanese temple nestled at the base of the Koolau Mountains. Kids love feeding the hundreds of koi fish in the pond and ringing the large brass peace bell. The temple and grounds are serene and beautiful with the dramatic green cliffs rising directly behind. Wild peacocks roam the grounds adding color and excitement. The whole visit takes about an hour and pairs perfectly with a stop at the nearby botanical garden. It is one of the most photogenic spots on the island.

The most iconic hike on Oahu and probably all of Hawaii. The 1.6-mile round trip trail climbs inside the crater of this famous volcanic tuff cone to the summit for panoramic views of Waikiki, the Pacific Ocean, and the Koolau Mountains. Kids love the tunnel, bunker, and steep staircase near the top that add adventure to the climb. The trail is paved but steep in sections. Reservations are required and the earlier you go the better to beat the heat and crowds.

A unique snorkeling spot where warm water discharged from a nearby power plant attracts an incredible diversity of marine life. Spinner dolphins, sea turtles, eagle rays, and dense schools of fish are regularly seen in the warm outflow channel. The visibility is good and the marine life density is higher than almost anywhere else on Oahu. The entry is over rocks and there are no lifeguards so this is best for experienced swimmer families. When conditions are calm, the snorkeling is genuinely world-class and free.

A protected marine bay set inside a volcanic crater with the best easy snorkeling on Oahu. The reef is teeming with colorful fish that swim right up to you in shallow water. Kids are mesmerized from the moment they put their face in. A mandatory short educational video before entry teaches kids about reef conservation which makes the experience more meaningful. The beach is sandy with a gentle slope into calm turquoise water. Arrive early because the parking lot fills fast and the preserve caps daily visitors.

A stunning 400-acre botanical garden set against the dramatic backdrop of the Koolau Mountains. The garden is free and has wide paved roads perfect for strollers along with trails through collections of tropical plants from around the world. Kids enjoy the catch-and-release fishing lake and the visitor center has nature activities. The mountain views from inside the garden are among the most photographed on Oahu. A campground within the garden offers free weekend camping with a permit, which is one of the best-kept secrets on the island.

Consistently rated one of the best beaches in America with soft white sand, turquoise water, and a gentle shore break that is perfect for kids. The water is warm and clear year-round and the beach stretches for 2.5 miles so you can always find space. Kayak rentals are available for paddling to the Mokulua Islands offshore. The park has restrooms, showers, lifeguards, and shady trees for picnics. Windsurfers and kiteboarders add entertainment for watching. The whole vibe is relaxed and family-friendly.