At 171 m long, the USS Pennsylvania is the biggest submarine in the US Navy. It can dive deeper than a thousand feet, sail for 20 years without refueling, and remain submerged for up to 6 months. The vessel carries a crew of 155 men and a deadly nuclear arsenal. This film explores how this submarine was made possible through a series of six historic engineering breakthroughs. The film explores the inner workings of six landmark submarines, including the tiny Turtle and colossal German U-Boats. Each features a major technological innovation that allowed engineers to build bigger and bigger submarines. The film explores the development of underwater breathing, torpedo's, missile launch syetems and stealth technology. Using high-end computer generated imagery that makes up 50% of the film, this film reveals the incredible stories behind these machines and the inventions that have enabled them to grow in size. Six ingenious leaps forward that enabled submarines to evolve …from BIG to BIGGER into the US Navy's BIGGEST.