The Mississippi River system and the Great Lakes are connected only through the man-made Chicago Sanitary and Ship Canal, which leads from Lake Michigan to the Illinois River.

And not just man. The whole Earth was made from dust particles in orbit around the primitive sun, as were all the other solid objects in the solar system.

Traditionally mariculture, involving the use of a system of man-made ponds in rearing specific Marine or brackish-water animals, has been practised in Indonesia for hundreds of years.