You can rest assured that digging at the beach (sand at Big Island beaches can be black, gray, white, or green!), goofing off in the ocean, snorkeling (at Kailua's fish-filled Kahulu'u Bay), and playing in the pools (check out the Hilton Waikoloa's epic water features) are going to be big hits with the kids on Hawaii's Big Island.
But there are other kid-friendly activities, too. Hilo's 'Imiloa Astronomy Center celebrates both astronomy (complete with hands-on exhibits and a planetarium) and Hawai'i's tradition of navigation by the stars. Kids (and adults) can learn more about nearby Mauna Kea, the mountain revered by Hawaiians where world-class astronomical observatories now make cutting-edge discoveries. And they can learn about how pre-contact Hawaiians made their own discoveries—using naked-eye astronomical observations and other methods to navigate the ocean. There's also a good restaurant there, with both American and Chinese food, where locals eat even when not visiting the Astronomy Center.
When Mokupapapa Discovery Center reopens in June 2013, down the street from its recent location in downtown Hilo, it will be in a space five times bigger than before. It's a great museum about the natural science, culture, and history of the uninhabited (except for some scientists and lots of wildlife) northwestern Hawaiian Islands that most people will never get to visit, and includes a salt-water aquarium, a mock-up of the Pisces V diving submersible with robotic arms that kids (or adults) can manipulate to pick things up off a simulated ocean floor, a theater, and lots more.
If you have extra time at the Kona Airport, check out the small Astronaut Ellison S. Onizuka Space Center, dedicated to the memory of Kona's own astronaut who died in the 1986 Challenger explosion. Onizuka's family runs this center, with Space Shuttle replicas, a real Apollo 13 space suit, hands-on exhibits, and videos about the history of manned space flight, physics and daily life in space—for instance, you can see astronauts brushing their teeth in space. It will thrill young ones who dream of being an astronaut.
Speaking of outer space, driving up Mauna Kea volcano to the Visitor Information Station (VIS) at 9,200 feet is a real adventure. (The observatories are at 13,000 feet, but it's not advisable to take children under 16 that high). The road up takes you across a geography so otherworldly that Apollo astronauts trained there thinking it would be like a trek across the moon, and roadside signs warn to beware of "invisible cows" (dark cows lying on dark asphalt, in fog). Between 6 and 10 pm there is free, guided stargazing at the VIS; it's above the clouds and is considered some of the best heavens viewing in the world.
The rural Big Island has a strong paniolo (Hawaiian cowboy) tradition. There's free-range horseback riding for any experience level at Dahana Ranch near Waimea (the ranch owner is sometimes called the Hawaiian Horse Whisperer). During a Waipi'o Valley horseback ride, the horses splash through rivers at the base of stunning waterfalls. Horseback riding is a great way to take in the beauty of Hawaii from outside a car.
You'll always see local moms strolling with their babies and toddlers at the Panaewa Rainforest Zoo and Gardens, not far from the Hilo Airport. It's a small, free, and absolutely lovely zoo and tropical rainforest botanical garden, which also has a fun area with play equipment for older kids. The zoo's most popular animal by far is Namaste, a white Bengal tiger and long-time zoo resident who lives in a well-appointed one-acre habitat and has a birthday party every year to which the community is invited. Namaste is very popular with Big Island kids (if you asked 10 random children around town, most could probably tell you his name). There's also a Primadome for primates, a petting zoo open daily from 1:30 to 2:30, and parents will enjoy the zoo's lovely gardens maintained by garden groups such as the Palm Society and Orchid Society. Bring a picnic lunch; there's a covered pavilion with benches in case the Hilo rain passes over.
Another great picnic spot is Liliuokalani Gardens, next to Hilo Bay, where families gather for walks, bike rides, fishing, roller-skating, and the like. Walk across the small nearby bridge to tiny Coconut Island and you'll find a calm place for kids to swim.
The Shops at Mauna Lani has a 4-D movie theater. Kailua-Kona has glass-bottom boat rides; to get up closer, biologists at the Ocean Rider Seahorse Farm in Kailua-Kona lead "Magical Seahorse Tours," where kids can feed and hold seahorses. Hilo's mall, the Prince Kuhio Plaza, has a bounce house place where, for a few dollars, kids can work off some excess energy.
If you're passing through Waimea, check out the excellent wooden park (at Lindsey and Kawaihae Roads) with swings, slides, and countless places to climb. Pick up a coffee from Starbucks in the nearby Parker Ranch Center, and then relax and enjoy the cool, upcountry Waimea air while your kids run and play.
Then it's off to the next adventure.
Photo credits: 'Imiloa Astronomy Center courtesy of 'Imiloa Astronomy Center; Mauna Kea via Shutterstock; Namaste at the Panaewa Rainforest Zoo and Gardens courtesy of Makuahine Pa'i Ki'i/Flickr; Hawaii Big Island via Shutterstock