Dual Jet Bath Spa / The Conair Dual Jet Bath Spa is a portable add-on that converts any plain old bath tub into an instrument of hot tub pleasure with a soothing water flow and bubble bursts. http://thegadgetflow.com/portfolio/dual-jet-bath-spa/
ALFI brand FireHotTub The Round Fire Burning Portable Outdoor Hot Bath Tub
The DutchTub, a "low-tech" jacuzzi that uses a very rudimentary heat exchanger coil to heat the water. This idea can be used for heating water via open flame, adjoining grills or stoves, coiling about exhaust stacks, generator exhaust tubes, solar heating units, or generally anything that generates a good amount of heat for any amount of time. In this way one can easily heat water, even large amounts of water, for survival, emergency or off-grid living conditions of any sort.