|| There are 5 Great lakes in the complex. Together they contain a significant percentage of the worlds total freshwater content. They are used for many recreational & commercial gains, including widespread pleasure boating, international shipping, commercial net fishing, & Angling. Along the shoreline are numerous towns & cities, including many camping & boat launching facilities. The Great lakes are also used in the production & cooling of electrical power generating stations. The Great lakes, no doubt, are one of several reasons why this area of N.A has become heavily populated. The total area of all five lakes (which are more correctly termed inland seas) is around 84,700 sq miles. When you consider that Lake Erie alone has about 900 miles of shoreline, you can well imagine the mind boggling challenge that such an area presents.