Unless you have a desire to hike Diamond Head specifically, I wouldn't recommend this hike. There were literally crowds of people trying to hike up the path to the top. Very, very touristy.
I'm glad we did it once but I have no desire to go again. If you decide to go, make sure you are there as early as possible so you can get parking and avoid the crowds!
Damien P. on Diamond Head (Le'ahi) Summit Trail
Thé 360deg view is howsome.
The views from this site were awesome, but the large volume of people on the trail with us made it difficult for me to find this trail relaxing in any respect. We went earlier in the day and it was already packed. I'm glad that I did it, but I don't think I would need to do it again. Bring water and wear appropriate shoes.