They wouldn't let me in to hike, because I didn't have a Hawai'i ID. I gave them my University of Hawai'i Faculty/Staff ID, as well as my South Carolina Driver's License, but it wasn't good enough. I even had my 5yr old daughter with me. Lame.
4.3mi out-and-back (not 2.6mi as listed), and a little over 1500ft elevation gain. Very similar stats to neighboring trails Kuli'ou'ou and Wiliwilinui. Of the three, Hawaii Loa is the most challenging with the steeper ascent in the second half of the trail. Very fun and beautiful trail. 2:30-3hrs if you're not in a rush.
Great hike. Fantastic views. It should be noted that security won't let you in unless you have a HI state ID or a military ID. The first half of the hike is easy and could even be a candidate for trail running as long as it hasn't rained too much and totally muddy. Be ready for some steep stairs for the second half as you follow the ridge line to the summit. This could be categorized as moderate to some.