Surf City is the fifth stage from Battletoads. It takes place on an underground river/aqueduct.
The first section of the stage is a simple obstacle course where the 'toads cross down a river on surfboards. The surfboard takes a while getting used to, since it bounces off the water. You must dodge incoming wooden logs and whirlpools, though they're not that hard to overcome.
After the whirlpools you come into the second section of the stage, which is set on foot. You only fight a few tall Walkers and 'Vaders, before facing Big Blag. Once he is defeated the player reaches the second obstacle course of the stage, which replaces the logs and whirlpools with floating mines. At some parts the player will also have to hit ramps to jump over waterfall chasms.