There are five gyres in the world's oceans. What's a gyre, you might ask. I thought the same thing when I first came across the concept.
The Mother of All Mothers | The Gyres of the Oceanic Circulatory System
Manmade Land | A Story of Land Reclaimation
Given the growing world population as well as the growth in world trade--I foresee this trend of land reclamation as eventually leading us down the path of looking for alternative sources of 'real estate' to meet the needs of a burgeoning population.