Garonne
The Garonne river starts in the Pyrenees. It runs for the first 50 kilometres in Spain at an altitude of 3000 metres, it then descends through a sink hole in the limestone and resurfaces above the Val d’Aran crossing the border into France. Along its course, the Garonne river meets the Dordogne River becoming the Gironde estuary which, about 60 miles later, joins the Atlantic Ocean. The Garonne river is one of the few rivers in the world that exhibits a tidal bore where surfers and jet skiers often gather to ride the waves. A tidal bore is a phenomenon by which a wave of water can flow back upriver. (The nearby Dordogne also has a tidal bore.)
The Garonne river allows vessels coming from the ocean to reach the port of Bordeaux , it also forms part of the Canal des Deux Mers, linking the Mediterranean sea to the Bay of Biscay. The Garonne river remains navigable for rather large boats until the Pont de Pierre in Bordeaux, at which point they cannot go any further. Smaller ships can navigate all the way up to the Midi Canal.