Water plays an important role in shaping the modern world. Cities are built on water. Humans rely on water for cooking, drinking, washing, transportation, trade, energy, irrigation (watering crops), and recreation. The use of water in the modern world has also created problems. Population growth and advancements in technology threaten the world's water supply. Overfishing and pollution stress many of the world's seas, and shortages of water stress human populations in arid (extremely dry) lands.

Cities and Ports

Most cities are located beside water, Coastal areas in particular boast large cities. Eight out of the top ten most populous cities in the world lie on the coast. Nearly 44% of the world's population lives within 100 miles (161 kilometers) of a coast. Coastal cities grow because ports are an integral part of modern life. A port is place where...