Why are boats in Venice twenty or thirty feet long, narrow and deep? Because Venice has many ancient buildings and narrow rivers, if there are many ships coming and going, you can't cross it, so you should make the ships narrow and deep. In this way, no matter how many boats there are, they can get by. The deep reason is that the boat is narrow and there is no place to put things. You can make the boat deeper and put things. Because they are narrow and deep, these ships are light and flexible. You got it?