Turbo Tunnel is the third stage from Battletoads, taking place on what appears to be the insides of a giant creature. Though it is probably the most infamous stage in the series due to the sudden spike in difficulty, it is merely a taste of what's to come.
The first section of the stage is a simple beat 'em up area where the player fights some Giblets and jumps across small chasms. Halfway through the player will have the first encounter with the 'Vaders.
The player will eventually hop onto the Speeder Bikes, which is where the real action starts. The first course introduces the most common barriers, with a simple alternating zigzag pattern. The second course introduces the ramps, which must be hit to jump across the larger chasms, as well as a floating barrier which will hit the player in case it jumps. Third course speeds up the action, adding floating ramps and Rat Rockets which will drop barriers in front of the player.
The fourth course gets even faster, adding only the Rat Pods which must be carefully dodged as well as chasms that must be jumped without the aid of the ramps. The final course is the toughest of them all, with alternating zigzag barriers which don't blink like the the previous ones and come lightning fast. There is a warp near the bottom of the screen in this section, after the 9th barrier, which will take the player straight to the 5th level, Surf City.