A hammock or a bath tub?

Certainly a bathtub, but exactly like a hammok is the new Vessel by Splinter Works:

The hammock bathtub is made from carbon fibre 

Like a suspended sculpture Vessel is one of the most unusual means for an artful relaxation. But how is how is it hanged?

It is fixed to the walls with stainless steel brackets. source 

Bathroom design is definitely one of the fastest developing areas of interior design. And a great field for applying designers' imagination and skills. Have a look at some more inspiring bathroom designs.