LL Cool J and Chris O'Donnell discuss tonight's season premiere of CBS's "NCIS: Los Angeles" which was mostly shot under water. O'Donnell says, "It was a huge tank of water that they built and they built the submarine. So, we filmed in the water. It was very uncomfortable...It was very smelly. LL Cool J reveals, "We spent a lot of time in the water...We were in the water for basically two weeks. It was really challenging."