Fjord Day (Fjordens Dag) is an annual nature-related observance held in Denmark on the second Sunday of September. It honors one of the most popular natural attractions of Scandinavia.

A fjord is a long, narrow inlet with steep sides or cliffs. It is formed when a glacier cuts a trough (U-shaped) valley by ice segregation and abrasion of the surrounding bedrock. Most fjords are deeper than the adjacent sea.

The employees of Skibhusgården, a nature and outdoor center in the Danish city of Odense, initiated Fjord Day in order to spread information about this unique natural phenomenon, increase the popularity of fjords among tourists, and emphasize the importance of preserving fjords and their biosphere.

The city of Odense is located near a 13 km long fjord of the same name that covers an area of about 63 square kilometers. Odense celebrated its first Fjord Day in 1991. Today, the celebration encompasses two Danish fjords, Odense and Kerteminde. It involves over 150 organizations, associations, schools and companies.