Right after the surfing we’ve headed to the Diamond Head Mountain. It’s a crater left from a volcano. It is circular shaped and it’s huge. You pass through a man-made tunnel to reach to the center of the crater. And then you start hiking up. It’s not really a hard hike but the view at the end is impressive. You see all of the Oahu under your feet. Also you see the bunkers they’ve used before to defend the island.