Awesome short hike, starts from the rocks across the street from the Halona Blowhole east of Honolulu [good place to park just above the beach]. It can be hot and windy as you are exposed all the way to the arch. The easier way to get under the arch is to hike around the left side while holding on to the rocks on your right. Most of the slope is covered with loose rocks and you will slip some. You can also go to the top in front of the arch and step to the right, but you need to be fairly tall to reach the handholds. Use common sense and caution, as a fall will cause an injury. The view is amazing and once you are under the arch, you have a nice place to sit and enjoy the breeze.
The best part of this trail is the view at the top, which is a 360 view of the crater, Hanauma Bay, Hawaii Kai, and beyond. That being said, the way up is pretty difficult. The stairs are old railroad tracks that go up the side of the mountain. I took it pretty slow with a few breaks along the way and it was fine. The way down was no problem, just watch your step!
There were definitely a good number of people out on the trail but not so much that it wasn't enjoyable.
Everyone was really nice. Plan on getting there early enough so you can get a parking spot. Also, I kind of wish I had brought a hat to keep the sun out of my eyes (sunglasses weren't really enough). Good luck!