The Sons of the Forest hang glider is one of the newest pieces of equipment added in the survival game's first major update, though it's more for fun than it is a necessary tool for coping with cannibals and starvation. The hang glider lets you fly from any elevated platform, so you can quickly move between the mountains to a forest camp without having to trek through the woods.
It's certainly a lot speedier and less time-consuming than setting up a network of ziplines, and with cheats, you could feasibly spawn one anywhere you want for a quick gliding getaway across the forest canopy. Either way, here's the Sons of the Forest hang glider location, and how to use it yourself, so you don't accidentally fly into the sea or something.
Sons of the Forest hang glider location
You can find the hang glider on a clifftop in the southwest edge of the mountains. The cliff itself faces over the forest directly below, so you won't have to climb too high to get to it. The two red tents nearby should help you locate it a little easier, though it should be simple to find using the map and GPS screenshots above.
Once you've located the hang glider, pick it up like any other item to equip it. You can begin flying by sprinting towards the cliff edge and jumping off it, but any elevated platform will do. While flying, use WASD to direct your path, though be aware that up and down are inverted. You can also look at your GPS while flying if you're trying to find a specific location. If you want to land, the good news is that all you have to do is fly into the ground to dismount, and it doesn't seem to hurt you even if you plummet directly downwards.
The bad news is that if you want to go again, you're going to have to carry it back to the mountains or to another elevated platform, since you can't store it in your inventory. However, if you've got console commands enabled you should just be able to spawn another.