No one wants to stand around in slime or muddy grass in an outdoor shower. Ipe stands up to water in the shower here, and the teak stepping stones provide an easy path back indoors. UPDATE: used IKEA outdoor flooring tiles
outdoor shower, corrugated metal - Could almost get away with one of these instead of trying to fit it into the inside bathroom. For a few months in "winter" it would be a bit chilly but still--fairly practical.