Guldborg Sund

thumb|400px|Guldborgsund between Falster and [[Lolland.]]

Guldborgsund is the strait between the Danish islands of Lolland and Falster. It connects Smålandsfarvandet in the north with the Bay of Mecklenburg in the south. The strait is about 30 kilometers long; its breadth varies from 150 meters at Guldborg to 6 kilometers south of Nykøbing Falster. It is navigable for craft of up to 6 metres draught in its northern part and is used for commercial traffic to Nykøbing Falster. The southern part is much shallower with a minimum depth of approximately 2 metres, and can only be used by yachts and other small craft.