The Titan sub and the dangers of the ocean floor

It's a story that's captivated the world: five men, who went deep into the Atlantic Ocean to try to get a glimpse of the wreckage of the Titanic, now presumed dead. So what do we know about the journey of the Titan submersible, in one of the most hostile environments on Earth?   Today, an oceanographer on the dangers and complexities of the mission.  Featured:  Arthur Trembanis, oceanographer at the University of Delaware