This article is currently a stub. It may – or may not – be expanded in the future.
Drehen's source is located near Laure-op-de-Drehen. A few kilometers down the river it connects with its tributary (TBD). The river flows through Domont, and on a short fragment is a border river between Welstand-Westrijk and Vinnmark. Further down the river there is Dreinationereck, a tripoint between Welstand-Westrijk, Vinnmark and Shilesia. From this point the river marks the border between Welstand-Westrijk and Shilesia, before splitting with the border, where it goes to the north and flows to the Firth of Hetzer.