The Am, the, Sane (which rises in the Faucilles and in the lower part of its course skirting the regions of Bresse and Dombes, receives the Doubs and joins the Rhone at Lyons), the Ardche and the Gard are the affluents on the right; on the left it is joined by the Arve, the Isre, the Drme and the Durance.
Its consistories are grouped into two special synods, one at Paris and one at Montbliard (for the department of Doubs and Haute-Sane and the territory of Belfort, where the churches of this denomination are principally situated).
The valley in which the town is situated used to be subject to inundations, but in 1805 a tunnel was constructed by means of which the surplus waters of the Bied are carried into the Doubs.
It is situated on the left bank of the river Doubs, 820 ft.
The citadel occupies the neck of the peninsula upon which the town stands; along the river bank in a semicircle is the town enceinte, and the suburb of Battant on the right bank of the Doubs is also "regularly" fortified as a bridge-head.