SECUREen.wikipedia.org/wiki/Waterbed
A waterbed, water mattress, or flotation mattress is a bed or mattress filled with water.Waterbeds intended for medical therapies appear in various reports through the 19th century. The modern version, invented in San Francisco and patented in 1971, became a popular consumer item in the United States through the 1980s with up to 20% of the market in 1986 and 22% in 1987.