This post comes as a special request from my biggest fan and most avid reader (or at least, the most avid commenter).
When you visit San Francisco, you have to see the Golden Gate Bridge. When you visit New York, you have to see the Statue of Liberty. When you visit Chicago, you have to see the Sears Tower (no apologies to the new name holders; I know it's not the Sears Tower anymore but I refuse to call it anything but Sears). When you visit Oahu, you have to hike Diamond Head (after seeing the Arizona Memorial, of course).
Diamond head is the most popular and accessible hike on the entire island. On any given day, the parking lot will be full by 8AM, and you can see people from all walks of life and fitness levels making the climb. It is a relatively short hike, and only has a few dozen stairs to navigate. My 3-year-old did this hike very easily, and proudly told everyone on the way down that he made it to the top.
Like many hikes here on Oahu, Diamond Head has a long history of serving other functions before it became a tourist trap. Once upon a time, it was an active volcano and helped form this part of the island. I won't bore you with the science, so instead I will give you this link to Wikipedia.
Then when the US military came to town, it set up a communications station and defensive position at Diamond Head. The military still owns and operates some facility here, but what you can see from the hike are the remnants of the pillboxes and other features that have long since been abandoned.
What makes Diamond Head one of the most universal trails on the island are its facilities. They have a bathroom with running water, a parking guard to keep your car from getting broken into, and a nice sign to take your picture in front of.
The trail itself is fairly well maintained. It is part concrete, part packed dirt. There are guard rails as you go up the switchbacks and climb the stairs to the lookout points. There is plenty of room to pass and be passed by other adventurers. There is one long tunnel that is now illuminated by running lights.
This is one hike where you don't feel like you are about to fall to your death with one wrong step. On the danger scale, I would put the Diamond Head hike somewhere between running with scissors and sticking your tongue to a frozen pole. Actually, nobody here in Hawaii would understand that last reference, so let's just say it's less dangerous than eating poke (raw fish dip).
The view from the top is pretty neat. You have a good view of Honolulu, Waikiki, and some of the surrounding features. In terms of scenery-per-effort, this is one of the best values on the island.
The real problem with this hike is getting a parking spot. Either you need to get here early and beat the jetlagged tourist rush, or you need to come during the hottest part of the afternoon (1PM ish). The parking lot is small, and if you don't get a spot you have to hike from down the hill somewhere. I would honestly say it would be better to find something else to do than to make the hike twice as far as it needs to be. So, get there early.
That is all there is to say about this hike: short, easy, running water, bad parking. Enjoy a few more random pics of this hike...