A 'hovercraft' can travel over water and flat terrain.
Source: Portobello_Solent_Express1_2007-07-28.jpg. http://en.wiktionary.org/wiki/File:Portobello_Solent_Express1_2007-07-28-cropped.jpg
Author: Portobello_Solent_Express1_2007-07-28.jpg: Klaus with K derivative work: Chris McKenna (Thryduulf (t