The extinct crater of Diamond Head is now a state monument, with picnic tables and a spectacular hiking trail up to the 760ft-high summit. The trail was built in 1908 to service military observation stations located along the crater rim.
Inside the crater rim, the park has information and historical displays, restrooms, drinking fountains and a picnic area. From Waikiki, catch bus 23 or 24; from the closest bus stop, it’s about a 20-minute walk to the trailhead. By car, take Monsarrat Ave to Diamond Head Rd and turn right immediately after passing Kapiʻolani Community College (KCC). Enter the park through Kahala Tunnel.