Here's some links to my favorite hiking resources. May they help you as much as they have helped me.
AllTrails - one of the best apps and websites out there when it comes to hiking. The app will input GoogleMaps directions to get you to the trailhead. The app also allows real time tracking of your location to determine if you are on the right trail. This is great for the many unmarked Hawaii Hikes.
Aloha from 808 - an awesome blog that includes a great variety of outdoor adventures. I'm a big fan of their expansive photo gallery.
Exploration Hawaii - Another great blog with some very solid hiking posts. This site is also great because it includes posts about good food spots on the island (everyone's gotta eat!).
GoHawaii - A great resource for travel to all the Hawaiian Islands. I especially like this one because it includes a lot of history about each individual island.
Hawaii Travel Guide - another awesome resource for all the Hawaiian islands. It's a good alternative to the overly touristy sites like Yelp and TripAdvisor when it comes to looking for things to do.
kenjiSAITO - a really great hiking blog with a great variety of hikes. This guy is really creative in the way he connects the different ridges on Oahu and always posts about his adventures. Still active as of 2018 too!
Unreal Hawaii - pretty much the ultimate guide when it comes to hiking and other outdoor activities in Oahu. A lot of my blog is drawn on inspiration from this digital magazine.
YouTube Channel: howzitboy - a great channel with some simple videos about how to do many of the hikes on Oahu.
YouTube Channel: Not So Good Hikers - Not only do these guys have a great username, but they also put out great videos that give very good directions on how to do many of the hikes on Oahu.