The North Quay in the port of Assens is closed to visiting vessels. Over the coming months, the Danish Environmental Protection Agency will be using this quay to dispatch 80,000 tonnes of natural stone for three new artificial reefs in the Little Belt. This may cause disruption in the port and the wider region.
The reason for this initiative is the destruction of the natural stone reefs in the 1960s. At that time, large quantities of rock were extracted from the sea to be used in construction projects elsewhere on land. However, this resulted in the destruction of a diverse habitat. The initiative now aims to renaturalise and restore this habitat.
According to the local council, the North Quay in Assens will be unavailable to visiting vessels until the work is completed. Anyone calling at Assens will therefore have to use the other berths. However, according to harbour manager Ole Knudsen, there are no restrictions on entering the harbour itself. The closure is expected to last around three to four months, probably until November 2026.
Noise and heavy goods traffic set to continue into winter
A total of 18 coastal freighters from Norway are due to dock one after the other at the Nordkai in Assens, each carrying around 4,500 tonnes of natural stone. Smaller specialist vessels will take over the cargo and transport it to the reef sites. From 15 September, three barges are to be loaded each day. According to the port operator, increased noise levels are to be expected in the marina between 6 am and 7 pm during this period.
What sailors need to bear in mind
Apart from the disruption caused by the construction work, the impact on sailors is likely to be manageable. Work is planned on the reefs off Helnæs North, Helnæs South and Lyø. The planning application stipulates that the topmost stones must remain at least five metres below the water’s surface. In one sub-area near Helnæs North, a depth of four metres is permitted. This means there will still be plenty of water beneath the keel for cruising yachts.
It is not yet known whether anchoring will continue to be permitted over the reef areas or whether restricted zones are planned. As new notices may be issued at any time during the construction phase, it is advisable to consult the Danish edition of the Notices to Mariners (BfS) before sailing in the area. Nautical Information from the Danish Maritime Authority.
Habitat restoration
According to the Danish Coastal Authority, the reason for this measure is the quarrying of stones in the 1960s. This caused lasting damage to the seabed. “That is why we have focused on large-scale restoration work, in the hope of attracting more macroalgae, sea anemones, crabs, fish and other marine life,” says project manager Rune Nielsen from the Environmental Protection Agency.
Active restoration is the only way to restore the lost habitat, the environmental agency had stated in the Motion argued to the Coastal Authority. Approval for the construction work was granted in December 2025. The project covers a total of ten hectares and, according to the municipality of Assens, is one of the largest projects of its kind in Danish history.
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David Ingelfinger
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