The border starts in the west at Cupecoy Bay and then proceeds eastward, cutting across Rue de Terre-Basses/Rhine Road. It then runs through the Simpson Bay Lagoon between the island of Little Key (Dutch) and Grand Islet (French). Back on land it crosses Rue de Hollande/Union Road and then turns north-eastwards, running across Sint Peter Hill, Mont des Accords, Concordia Hill, Marigot Hill, Mount Reward and Mount Flagstaff.