History: Bathing Machine Devices On The Beach, 18th-19th Century, Europe

Especially in Britain, men and women were usually segregated, so nobody of the opposite sex might catch sight of them in their bathing suits, which (although extremely modest by modern standards) were not considered proper clothing in which to be seen.
Use
Four-wheeled carriages, covered with canvas, and having at one end of them an umbrella of the same materials which is let down to the surface of the water, so that the bather descending from the machine by a few steps is concealed from the public view, whereby the most refined female is enabled to enjoy the advantages of the sea with the strictest delicacy.