@ray666 Hi, Ray. Yesterday I went nautical. Great fun and excellent exercise. Working with - or against the buoyancy and against the resistance of the water. The tank had a treadmill in the bottom, a fold-down seat for seated exercises, grab bars on 3, or maybe all 4, sides. Tank was maybe 3 x 5 feet and water could come up to my armpits, and tank was full to chest high; PT-ist could raise or lower the water depth with an easy-to-operate control. Water temp was higher than I expected, but movement is quite limited so it needs to be higher than a swimming pool. Tank appeared to be plexi-glass. To enter the tank, I stepped into a side compartment, the door was locked, and it filled with water to about waist height; then the door to the main tank was opened, I stepped in, and the water in the side chamber emptied possibly into a separate steel tank where it was temperature adjusted. It was great fun and I'm going in the tank again next week! The PT-ist will get me back in the municipal pool yet (in Mobility through Water groups).