This illustration shows how Scarlet Knight, the first unmanned, underwater robot or glider to cross an ocean basin, faced an entire fleet of fishing ships, equipped with nets, threatening the glider’s path across the continental shelf. “Crossing the shelf is like running across the New Jersey Turnpike with your eyes closed,” said filmmaker Dena Siedel in the documentary Atlantic Crossing: A Robot’s Daring Mission. The robotic glider crossed the Atlantic in 2009.