Watsu was developed by Harold Dull in California, USA, in 1980.
Harold brought Zen Shiatsu techniques into the water, that is, in warm water (usually in a pool). He found that working in water with a client could bring additional health benefits, notably inducing deep relaxation.
Watsu combines muscle stretching, joint mobilization, massage, Shiatsu, and dance in warm water of around 35°C. The receiver is continuously supported, typically floating on his or her back, while the therapist cradles, moves, stretches, and massages the receiver.
Learn more about Watsu at the official Watsu Website.