A coastline made of craters
Southeast Oʻahu is the island's youngest volcanic ground, a chain of late eruptions that left the coast dotted with tuff cones: Diamond Head, Koko Head and the flooded crater of Hanauma Bay. The highway threads between them with the ocean close enough to feel the spray.
The day begins at the Diamond Head Lookout, where Leʻahi frames Waikiki and the morning surf. East of there, the road passes the homes of Kahala before the landscape turns wild.
Hanauma, Halona and the blowhole
Hanauma Bay, a crater opened to the sea, is Oʻahu's best-known snorkeling preserve, with its own reservation system. The tour passes above it rather than stopping to swim. A few bends later comes the Halona Blowhole, where swells force seawater through a lava tube and up into the air. The cove beside it is the beach from From Here to Eternity.
Next door, Sandy Beach has one of the island's most powerful shore breaks, loved by expert bodysurfers and best watched by everyone else. In winter, every lookout on this stretch doubles as a whale-watching spot.
Makapuʻu and the turn north
The coast ends at Makapuʻu Point, where a lighthouse has stood since 1909 above offshore islets that shelter seabirds. Round the point and the Koʻolau cliffs rise ahead as the road turns onto the windward coast.
Tour stops on this coast
Diamond Head Lookout
Morning light over Waikiki from the seaward flank of Oʻahu's most famous crater.
Halona Blowhole
Ocean swells forced through an old lava tube and blasted skyward, sometimes 30 feet high.
The tour also passes Kahala, the Hanauma Bay rim, Koko Head, Sandy Beach and Makapuʻu.