The HotTug is a wood-fired hot tub that you can sail and a tug boat in which you can soak in a delicious warm bath. It is ideal for carefree fun and relaxation on the water, moving or stationary, ready to take you to idyllic spots for a visit or a swim. This ingenious little boat is made from wood and fitted with glass fiber reinforced polyester, uses a stainless steel stove with a single wall pipe to keep the water as warm as you like, and is powered by either an electric or standard outboard motor. It heats the 2000 litres of water in the HotTug to a pleasant 38 degrees Celsius in a few hours.

Source: http://www.hottug.nl/hottug_en.htm