A mud sledge is a sled used to cross mud flats such as estuaries and bays.
Mud flats are difficult to cross because even shallow draft boats will get stuck while pedestrians and wheeled vehicles bog down easily too. A mud sledge is a traditional device used by fishermen when they collect from nets, pots and traps which they set out in tidal waters. The traditional designs vary but, typically, they have a flat wooden base and are propelled by scooting with one or both legs.
Traditional fishing in this way has declined in modern industrial countries, but the sledges may still be used for races and sport.