Fly an aircraft to the farthest northwest island. Stunt Jump out of the place once lightning hits it, and parachute to the island. You will find parts from crashed airliner Oceanic 815 from Lost around the beach where “Search” is written in the sand (X:1275, Y:3663 coordinates). Go to the southwest corner of the island (X:1743, Y:4363 coordinates) to find the mysterious hatch from Lost. You can also hear sounds of the “black smoke” monster while on the island.
Go to X:7392, Y:16151 coordinates. You can ride inside the balloon by shooting off the sandbags. Your direction in the balloon can be controlled by walking in the basket. You can also find an armor piece near the balloon.