Cousteau's Sea is a documentary series created by Jacques Cousteau, a French oceanographer and filmmaker. The series follows Cousteau and his team as they explore the world's oceans and document their findings. The term MER, which is the answer to the crossword puzzle, stands for 'Mer et l'AIR, ' which translates to 'Sea and AIR' in English. This phrase was used by Cousteau to describe his exploration of the sea and the AIR above it.