Published in 1976, this has a great little introduction to submarines in history (I like history books). Originally they were used to raise naval blockades by stealth. Meaning, shooting at ships at night. Gunston says that the Pacific Ocean is larger in surface area than all the land on earth and it's depths have only recently been measured. The USS Holland (1898) is considered the first modern submarine and the Lake's Protector (1902) the first to make an ocean voyage from Norfolk, Va to New York. The author is writing when submarines with ballistic missiles were feared war machines and compared only with Navy carriers for being able to threaten a whole territory. Subs and carriers are also the most expensive to build. Subs are now also used for ocean research and their technology is put to peacetime uses. ( )