Laminaria hyperborea is a species of large brown alga, a kelp in the family Laminariaceae, also known by the common names of tangle and cuvie.

[5] Laminaria hyperborea can be distinguished from the rather similar L. digitata by being paler in colour and having a longer stipe which snaps when it is bent sharply.

[8] Laminaria hyperborea can liberate upward of a million zoospores from sori on the surface of the blade during the course of a few weeks during the winter.

[8] Sexual reproduction is dependent on a minimum quantity of blue light; under less than optimal conditions, the gametophytes may develop vegetatively instead.

[18] The stipes, being rough, provided good anchor points for Palmaria palmata and several other species of red algae.

[17] The holdfasts offered a sheltered refuge and housed a large number of mobile macrofauna, a community that was quite different from that on the stipes.

[17] In a study undertaken on the north east coast of Britain, 61 different species of nematode were found living in the holdfasts of L. hyperborea.

[19] In another study comparing the macrofauna resident in the holfasts of L. hyperborea round the coasts of Britain, it was found that, except for the suspension feeders, there was an inverse relationship between the richness of the flora and the pollution, as measured by the heavy metal content of the water, and its clarity.

A study found that it could produce annual increases in biomass of 16.5 and 8.0 metric tons of organic matter per hectare at depths of 3 and 9 metres respectively.