Who would have thought that Leonardo da Vinci invented the Submarine? The sad thing was that Da Vinci kept his plans secret because he didn't want to make war any scarier than it already was. Since Da Vinci kept his plans secret other people had to come up with their own plans. The next person to draw up plans for a submarine was William Borne. William Borne began drawing up his plans in 1578. Although Borne's submarine was never built he had a great idea. His plan was to put extra tanks into the submarine. When the tanks filled the Submarine would submerge but when the tanks emptied the submarine would surface. So Borne had a great idea on how to make something sink or swim. Now let's go on to Cornelis Drebbel. Cornelis Drebbel was a Dutch inventor. He created a leather covered rowboat with oars in 1620. Drebbel had gotten the idea of the "rowboat" from Da Vinci. The "rowboat" could fit twelve people at the maximum. The "rowboat" could only go under water for about fifteen feet but it could stay under for a couple of hours. Looking back at all of the different models of the submarine we can tell that each inventor had a different opinion. We will never know what Da Vinci's ideas were but we do know what Borne's and Drebbel's ideas were. Borne had the idea to put tanks inside of the submarine that controlled when the submarine sunk and when it surfaced. Looking at Drebbel's ideas we see that he had the idea of people controlling when the submarine sunk and when it surfaced. So looking at those two different ideas we can see which one is more modern. In my personal opinion I think that Borne had a more modern idea than Drebbel
Drebbel's Idea 
Modern 