The hike distance isn't long but it is steep. Be sure to wear tennis shoes or hiking shoes (although there were many people doing it in flip flops, ballet flats, and sandals-totally ridiculous!) My calves were reminding me of the hike for days! I would recommend going as early as possible before it get too hot. No need in our opinion to make the addition walk from the first parking lot through the road tunnel (very narrow walking pathway). We parked in the 5.00 lot and went from there. Great views and several stopping points for looking out. There is a loooong, narrow, dark tunnel to to through. Once through the tunnel go right for STEEP steps up to the top or go left for an easier ascent with less steep stairs.
If you own or manage Diamond Head, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.