If for whatever reason you don't want a Rolex then take a look at the Blancpain Fifty Fathoms Bathyscaphe. It's water resistant to the usual 300m, is a more comfortable 43mm wide (and 13.40mm deep) and even includes a transparent case back, which is a feature less often found on dive watches; though, this may be due to the increased thickness they give a watches case, the perceived weakness that they give and the additional cost involved.
Perhaps the most recognisable watch on the face of the planet - the Rolex Submariner is such a tremendously iconic and timeless design, from the biggest luxury watch brand in the world.
Throughout wristwatch history Rolex have forever been at the forefront of innovation. They are known as the first major manufacturer of a completely water-resistant divers watch thanks to a series of landmark publicity stunts to promote their brand. They put another mark into the history books with the Datejust that automatically adjusted the date by itself - an unheard of accomplishment at the time. And they are also attributed with the first watch to show two-time zones with the GMT master.