The tentacle is an appendage from an unnamed Wasteland creature in Jak 3 that lives near the waters of the Wasteland and Spargus coast. It is simply a game mechanic, used to prevent players from going out too far into the water. There is little warning of the enemy's appearance, aside from a few surfacing bubbles, as it is usually instant in activation where it will snare Jak suddenly and swallow him.
In Spargus, the proximity is to the small island shortly ahead of the gun turret. In the Wasteland, activation is quick and short, giving the player little to no room in the water.
The tentacle is unbeatable and cannot be bypassed;[a] if Jak attempts to use the JET-Board, he will simply dismount it the second the bubbles begin to rise. Light Jak's Flash Freeze is incapable of escaping the tentacle's reaction time.