Ron Miller, writing for io9:
In 1874, Captain Francois-Elie Roudaire, a geographer in the French army proposed a daring idea. No doubt inspired by the successful completion of the Suez canal a few years earlier, he suggested the creation of a 120-mile-long canal that would connect the Mediterranean Sea to a part of the Sahara Desert in Algeria that lies below sea level. The result would be the flooding of more than 3000 square miles of territory. Roudaire hoped that such a huge body of water would not only allow ships to navigate into the interior of North Africa, it would also significantly change the local climate. All at a cost of a mere 25 million francs.
Contrast that with Atlantropa, which sought to shrink the Mediterranean to give Southern Europe and Northern Africa more land.