The summit of Diamond Head gives you some remarkable views of Oahu. The climb to the summit is a moderate 0.8 mile ascent mostly up a series of stairs that gains 560′ of elevation. The trail was built in 1908 as part of the coastal defense system. The view from the summit is awesome. Looking down will give you an impressive view of the clear ocean waters and the Diamond Head Lighthouse.
At the summit be sure to hold on to your hat, literally. The winds at the top can be swift and you will see many, many hats dotting the cliffs below the viewing area. This is a very popular spot so plan accordingly. I went early in the morning and it was moderately crowded but not too bad. When I returned to the parking there were many more cars and tour buses.
There is a concrete bunker on the summit that is the Fire Control Station completed in 1911. The last leg of the ascent is through a lighted 225-foot tunnel. This station directed artillery fire from batteries in Waikiki and Fort Ruger outside Diamond Head crater.
My favorite view was of the Diamond Head Lighthouse. The water was so clear that the seabed made changing patterns as viewed through the water.