South of Waikiki in Diamond Head State Monument on Oahu, the Diamond Head Crater Trail is a 1.6 mile round trip route with 560 feet of climbing. The Diamond Head Crater Trail winds up the inside of an extinct volcanic crater to the summit. You'll need to pass through a 225 tunnel on the way to the top. From the summit, you'll be treated to views of the Waianae Mountains and the Koko Head Crater.
Overall, Diamond Head Crater Trail is the 26th most popular hiking trail of all 45 hikes in Hawaii.