sentences:  These practical factors make watch depth ratings of more than marketing curiosities.In late March 2012, Rolex announced that a new prototype diving watch was developed and is part of the Rolex supported attempt to dive the DSV "Deepsea Challenger" to the bottom of the Challenger Deep, the deepest surveyed point in the oceans.On 26 March 2012 the DSV "Deepsea Challenger" carried a Rolex Oyster Perpetual Date Sea-Dweller DEEPSEA CHALLENGE prototype diving watch strapped to its manipulator arm to a depth of of seawater (msw).