Just Cause

I haven't found a video of someone actually unlocking it yet or with a map, so I decided to make one. The safehouse is the Eagle's Nest, the 4th Rioja base, which you will unlock after accumulating enough Rioja points.

You do not need to have unlocked the safehouse, but it makes it easier. Having helicopters available will also help.

Here is the video you suggested.

There's a cliff edge a small wander north from the Eagles Nest base camp.

You need to jump off the edge of the cliff and freefall for ages, through the tree canopy at the bottom (be brave!) and only pull the chute right as you are about to hit the deck.

If you can't find the cliff to jump from, took me a number of times until I got it right, or you just don't want to wait then you can create your own base jump. There is a glitch in Just Cause that allows Rico to continually jump higher. First you need to find the Adler FF M-72, you might be able to do this with another weapon but I was not able to. Equip the weapon. Run forward and jump. At the height of the jump change weapons to the Protec Grappler G3. Rico will jump again from that height. About a half second later swap back to the Adler and another half second swap back to the Grappler. Each time you swap weapons Rico will jump again. You can swap faster but Rico will not jump as high. If you swap too slow Rico will not jump again and will fall. Continue to swap these two weapons until you think you are a thousand meters up - this is a lot higher than I first thought. Stop swapping weapons and left Rico fall for a thousand meters. The achievement will pop when you deploy the parachute. Keep in mind that at the peak of jumping allow Rico to fall the thousand meters other wise the base jump won't count. I found this is easiest to do near water because there are no obstacles. Potentially this could be done from a mountain top as long as Rico freefalls for a thousand meters. If you did not get the achievement then check the stats screen to see how far you really fell and adjust accordingly.