Le Treport, situated at the mouth of La Bresle, is a small port used by commercial vessels, fishing boats, and recreational craft. It consists of Avant-port, which dries, and two wet basins.
Le Treport stands on the SW side of the harbor and the smaller town of Mers-les-Bains stands on the NE side.
The tides rise 9.4m at springs and 7.5m at neaps. Strong onshore winds cause a heavy scend in the outer harbor.
Several quays border Avant-port and dry 4 to 5m, with a bottom of soft mud. Part of Quai Bellot, on the N side, is used by recreational craft.
Port du Peche (Fishing Port) et de Plaisance is entered from the SE end of Avant-port through a lock, 28m long and 9.5m wide. It is used by fishing vessels and recreational craft.
Port du Commerce is entered from the NE end of Avant-port through a dock gate, which is 19m wide and has a depth of 2m on the sill.