Swamp Buggy Day races: Naples, Florida 1953.

"The Swamp Buggy is a vehicle used to traverse boggy swamp terrain. They must be able to move about on dry land, shallow mud, and shallow water. Additionally they possess one or more of the following abilities:
Propel itself through or over deep mud and water
Drive through or over moderately dense vegetation
Drive over rough terrain possibly including logs and stumps
Float in water or mud"

Image source: http://www.thegentlemanracer.com/2012/08/swamp-buggy-day-races-naples-florida.html

Text source: http://en.wikipedia.org/wiki/Swamp_buggy