The Limfjord (common Danish: Limfjorden [ˈliːmˌfjoˀɐn], in northwest Jutlandish dialect: Æ Limfjord) is a shallow part of the sea, located in Denmark where it has been regarded as an inlet ever since Viking times. However, it now has entries both from the North Sea and Kattegat, and hence separates the North Jutlandic Island (Danish: Nørrejyske Ø, which includes the old provinces of Vendsyssel, Han herred and Thy) from the rest of the Jutland Peninsula. The Limfjord extends from Thyborøn Channel on the North Sea to Hals on the Kattegat. It is approximately 180 kilometres (111 miles) long and of an irregular shape with numerous bays, narrowings, and islands, most notably Mors, and the smaller ones Fur, Venø, Jegindø, Egholm and Livø. It is deepest at Hvalpsund (24 metres).
Its main port is Aalborg, where a railway bridge (Jernbanebroen over Limfjorden) and road bridge (Limfjordsbroen) have been built across the Limfjord to Nørresundby, while motorway E45 crosses it through a tunnel to the east. Commercial ports also exist at Thisted, Nykøbing Mors, Skive, Løgstør, Struer, Lemvig and Thyborøn. There are also bridges at Oddesund, Sallingsund, Vilsund, Aggersund and Sebbersund, and a number of ferry crossings.