6 Best Sights in Hawaii Kai, Oahu

Picture this as the world's biggest open-air aquarium: you come to see fish, and fish you'll see. Due to their exposure to thousands of visitors every week, these fish are more like family pets than the skittish marine life you might expect. An old volcanic crater has created a haven from the waves where the coral has thrived. Note that there's a fee for nonresidents to enter the preserve; make reservations and prepay online ahead of time (locals have a morning time period where they can walk in without a reservation). You must also watch a nine-minute video about the nature preserve in its educational center before being allowed down to the bay. Snorkel equipment and lockers are available for rent, and you can walk the short distance from the parking lot or take a tram. It's best to visit early in the morning (around 7), as it's difficult to park later in the day. Need transportation? Take TheBus each way from anywhere on the island. Amenities: food and drink; lifeguards; parking (fee); showers; toilets. Best for: snorkeling; swimming.

Very popular with locals, this broad, sloping beach is covered with sunbathers who come to soak up the rays and watch "The Show"—a shore break that's like no other in the Islands. Monster ocean swells rolling into the beach combined with the sudden rise in the ocean floor cause waves to jack up and crash magnificently. Expert surfers and bodyboarders young and old brave the dangers to enjoy some of the biggest barrels around.  Use extreme caution when swimming here. The stretch is nicknamed Break-Neck Beach for a reason: many neck and back injuries are sustained here each year. Amenities: lifeguards; parking (no fee); showers; toilets. Best for: walking.

Below a scenic turnout along the Koko Head shoreline, this oft-photographed lava tube sucks the ocean in and spits it out. Don't get too close, as conditions can get dangerous. Look to your right to see the tiny beach below that was used to film the wave-washed love scene in From Here to Eternity. In winter, this is a good spot to watch whales at play. Offshore, the island of Molokai calls like a distant siren, and, every once in a while, Lanai is visible in blue silhouette. Take your valuables with you, and lock your car, because this popular scenic location is a hot spot for petty thieves.

Also known as Eternity Beach, this little beauty is never crowded due to the short, treacherous climb down to the sand. But what a treat it is for the intrepid—perfect for packing a lunch and holing up for the day. The beach is in a break in the ocean cliffs, with the surrounding crags providing protection from the wind. Open-ocean waves roll up onto the sand, but a gently sloping sand bottom takes much of the punch out of them before they hit the shore. Locals also call it "Cockroach Cove," but there's no consensus as to why. Turtles frequent the small cove, seeking respite from the otherwise blustery coast.  The current is mellow inside the cove but dangerous once you get outside it. Amenities: parking (no fee). Best for: sunrise.

If you've visited any of Oahu's other botanical gardens, Koko Crater will stand in stark contrast. Inside the tallest tuff (a type of volcanic rock) cone on Oahu, in one of the island's hottest and driest areas, the garden showcases dryland species of plants, including baobab trees, cacti, plumeria, and bougainvillea. Bring plenty of water, sunscreen, and a hat. Though it's close to Oahu's more lush windward side, this is a scorching spot.

A little more than a ½ mile past Hanauma Bay as you head toward Makapuu Point, you'll see a turnout on the ocean side with some fine views of the coastline. In winter, you'll have an opportunity to see storm-generated waves crashing against lava cliffs. This is also a popular place for winter whale-watching, so bring your binoculars, some sunscreen, and a picnic lunch, and join the small crowd scanning for telltale white spouts of water only a few hundred yards away. On clear days, you should be able to see the islands of Molokai and Lanai off in the distance, hence the name.