Through Iberia does not make much sense, as the mountains separating the Mediterranean and Atlantic watersheds are a bit too high. An alternative route is through the French river systems, an incarnation of which was the Canal du Midi, linking the Garonne with the Mediterranean, and finished under the rule of Louis XIV in 1681. The purpose was on the one hand commercial, but on the other also political, connecting Southern France into a broader French cultural identity and bypassing Habsburg Spain and Mediterranean piracy.

For an overview of the Canal du Midi, see René Gast 2000, The Canal du Midi and the navigable waterways from the Atlantic to the Mediterranean. The various political and historical contexts of the Canal have been treated in a number of very interesting publications by Chandra Mukerji.