It then passes through Bohars and Guilers (a village bears the river's name) before it flows out into the roadstead of Brest.

The Penfeld runs along the former course of the river Aulne, shifted to the west by the opening of the goulet of the roadstead of Brest by the interglacial periods of the Quaternary Era.

That explains its depth, which allows deep-draught ships to go quite a way upstream, with tides running up it up to 8 m (26 ft) deep.

In its last stretch, within embankments 25–30 m (82–98 ft) high, the Penfeld runs through the Brest naval base, and at its mouth (a site whose strategic importance has been recognised since antiquity) is the 15th-century Château de Brest.

You can help Wikipedia by expanding it.This article related to a river in France is a stub.