My mother, when re-doing her bathroom, installed a shower stall and a "soaking tub", which is shorter head-to-foot than a typical American tub, but much deeper. It may also be a trifle broader. As I recall, she went to the extent of importing one from Japan and was immensely vexed to find out that the seller had listed the overall dimensions, not the inner dimensions, thus completely messing up her carefully-planned-out design.