To many people, the island of Oahu is synonymous with its capital city, Honolulu. More specifically, the 2.5-mile stretch of sand that is Waikiki Beach. And while the vast majority of visitors here never stray far from Waikiki's glittering shore—which offers everything one might want on a beach vacation, except for privacy—those who do venture beyond the tourist zone will find more than 100 miles of coastline fringed with beaches of every size, shape, color, and activity orientation.

Surfing dominates the beach scene on Oahu. The North Shore is home to some of the most beautiful, famous, and dangerous waves in the world. During the winter, check whether the surf is up at Pipeline or Waimea Bay; if so, don't miss the opportunity to see world-class surfers in action. Novices and intermediates are better served on Waikiki, where consistently small waves made this the birthplace of modern surf schools.

During the summer, the North Shore undergoes an incredible transformation. Lake-calm waters replace 30-foot waves, turning Waimea Bay and Pupukea Beach Park into popular snorkeling, swimming, and lounging destinations. No matter what the season, though, keep in mind that when the conditions are rough on one side of the island, the opposite shore will usually be flat calm and ideal for lower-impact activities.

Some of the most popular beaches outside of Honolulu can be found east of the city and along the windward coast. About ten miles from Waikiki is Hanauma Bay, a marine protected area and one of the island's most popular snorkeling spots. A little farther past Hanauma sits Sandy Beach, where hardcore bodyboarders rip on a pounding shore break. The windward coast often has the calmest sea conditions, though as its orientation implies, there are steady winds here, making for good windsurfing at spots like Kailua Beach Park. The Mokula Islands off Lanikai Beach are seabird sanctuaries and make a good sea-kayaking destination.

To really beat the crowds, consider making the drive to the Waianae Coast on the leeward side. Pokai and Yokohama Bays are popular local hangouts, which offer good swimming, snorkeling, and beautiful sandy stretches of shoreline. As with most parts of the island, however, be cautious about going in the water here if the waves are up.