This is a very doable yet challenging hike. It’s all ascending and steep and there is a section where I’d advise taking the “alternate route” instead of going over the railway. With that said, plenty of people didn’t take the alternate route and you’ll see others literally running up/down without missing a step. If you’re on vacation, don’t ruin your vacation getting hurt. There are plenty of other hikes you want to stay healthy and injury free for.
With that said, I saw plenty of people in flip flops. Don’t do this. Most of the people that get hurt on these trails do not come even a little bit prepared. If you’re a Teva user, no these aren’t hiking shoes. There’s lot of dry dirt at Koko and in most of the Oahu trails and Tevas roll right over the dirt causing you to lose your footing.
You’re doing this hike for the thrill and the challenge for sure. There are some decent views at the top, but the summit itself isn’t all that nice. I’d recommend it in the early morning or time it for sunset. If you go during sunset, be prepared to sweat a lot and pack lots of water!Also, if you do it for sunset, you’ll likely be doing a portion of the hike back down in the dark. You’ll be in good company, but be extra careful and even consider a flashlight.