At the centre of the main continent are four seas. Like the four chambers of a heart. Each sea has a current, each is fed by major rivers. Yet each will have an outlet to the chaos. A waterfall as wide as the Straights of Gibralter. This is where the Mediterranean Sea runs into the Atlantic Ocean.

Another feature to consider is for the feeding rivers are all the same. In Europe there are long rivers that are navigable. In North America there is a major navigable network of rivers with one outlet to the Mexican Gulf. In Africa apart from the Nile, rivers drop from large heights through rapids. These rivers are not navigable. This has resulted in different affects on local economies.

Many things to consider.