Most clawfoot tubs are generally not always as deep as you would expect. This is the deepest in a double ended slipper that we have.

You can see a schematic for this tub here:
http://www.classicclawfoottubs.com/schematics/71-cast-iron-double-ended-slipper-clawfoot-tub-imperial-feet-scematic.jpg

As far as our DEEPEST soaker tub, here is a link to a model that is the deepest we carry. However, it's not a double ended tub.
http://www.classicclawfoottubs.com/57-cast-iron-swedish-slipper-clawfoot-tub.html

I hope this helps a little.