Passantenhaven Marsdijk is a small transit marina on the Noord-Willemskanaal, situated at kilometre 22. 6 on the canal's left bank near the Marsdijk neighbourhood of Assen.

It lies roughly halfway between the junction with the Drentse Hoofdvaart and Sluis Peelo, making it a convenient stopping point for boaters travelling between Groningen and the centre of Assen.

The harbour offers shore power (16-ampere posts) and a waste container, accessible in consultation with the harbourmaster. Winter storage permits can be requested for the period from 30 September onward.

Mooring fees are charged at a flat rate regardless of boat length, and the harbourmaster can be reached by phone or email upon arrival.