Invisible Barriers, also known as Invisible Walls, are preventative measures integrated into the game to prevent the player from leaving the game world. This feature can be found in 3D Universe games and above. They kill the player in a variety of ways, from just blowing up the player in a boat, to taking a wing off a player's jet. There are three types of ways the player can be killed by the barriers.
All GTA games in the 3D Universe have similar mechanics for keeping the player confined to their game world.
In GTA III and GTA Vice City, if the player flies far enough outwards towards the ocean, after reaching a certain point, the game will immediately turn the player's vehicle around. For example, if the player flew a Skimmer straight north in GTA Vice City, after a few minutes, the Skimmer will suddenly be turned around, so it is pointing the opposite direction, but it will still be going the same speed as it was before. GTA Liberty City Stories and GTA Vice City Stories retain this feature. In GTA San Andreas, the world technically lasts forever, as oceans generate as the player flies far enough from the game world. This was done, because the player has to go to Liberty City in the mission Saint Mark's Bistro. If the player flies far enough from the land for about half an hour in real life time, the player's airplane will explode, although this is a rare occurrence in the game.
In GTA IV, a vehicle will explode after only a few miles from shore. Messages will pop up on the screen, taunting the player to return to Liberty City. In Grand Theft Auto V, if the player flies an airplane as far as possible in any direction, after a while, one or both of the plane's wings will suddenly get torn off the plane's fuselage, making it plummet down into the ocean. Sometimes, the plane simply explodes altogether. In other cases, the plane will simply cut off, and begin gliding toward the ocean. This happens with boats and helicopters. This also happens in GTA Online.
If the player exits the plane unharmed and is floating in the water, after some time, he will begin losing health and will eventually die. Similarly, if the player bails out of the downing aircraft and deploys the parachute, the player's chute will disappear, causing the player to fall to death. He will hit the water's surface at full speed, killing him instantly. If the player makes it to the water, sharks will spawn and try to kill the player.
There are also invisible barriers in GTA Chinatown Wars, which are not deadly. When the player uses a boat and goes far away from map, an invisible barrier will stop them.