Grand Bassin
![Castelnaudary's Grand Bassin43°18′50″N 1°57′24″E / 43.31389°N 1.95673°E / 43.31389; 1.95673](/Images/godic/202501/16/Castelnaudary_bassin_canal0503.jpg")
The Grand Bassin is the largest body of open water along the Canal du Midi. It is in Castelnaudary France and covers some 7 hectares (18 acres). Once a scene of intense economic activity, it is now a major pleasure port used by tourist craft. It holds the water reserve for the four locks of Saint-Roche.