This assumes very little experience in script knowledge, more expedient ways to repro would be appreciated.
1. In the editor, choose Stratis.
2. Create a helicopter (MH-9) over deep water, like the top left corner of the map
3. Set the helicopter to "Flying", set the elevation 500 and in the init field write "this flyinheight 500"
4. Create a soldier, set it in the same squad as the helicopter
5. Set the soldier's mode into "In Cargo"
6. Preview
7. Access the helicopter's inventory and place the steerable parachute backpack onto your backpack slot
8. Eject
9. In freefall, deploy the parachute when you are very close to the water.
Note: If you hit the ocean floor, you will die.