A fjord is a deep, narrow and elongated sea or lakedrain, with steep land on three sides. The opening toward the sea is called the mouth of the fjord, and is often shallow. The fjord's inner part is called the sea bottom. If the geological formation is wider than it is long, it is not a fjord. Then it is a bay or cove.

The fjords were formed by the giant glacier tongues that through several ice ages have shaped the landscape. A fjord is thus a U-shaped undersea valley, and on the west coast, this valley is often surrounded by dramatic mountain scenery.

In front of the glacier arm, there was deposited a moraine of gravel and sand that formed an underwater barrier, often called "sea thresholds" or "ra". Places where the fjord is shallow.

This shallow threshold in the mouth of the fjord, is the reason that fjords often are quieter than the open sea. Thus fjords are often natural harbors. Fjord is one of the few Norwegian words that have become international, especially in English where it is used directly. Fjord comes from the Norse fjǫrðr. This stems, in turn, from the prehistoric Indo-European word *prtús, derived from *por* or *per, meaning "go", "pass" or "to put over on the other side."

Fjord in its basic meaning "where one fares through", then has the same origin that the word "fare" (travel). The verb "fare" and the noun "ferry", has the same origin.

The longest fjord in the world is Scoresby Sund in Greenland (350 km), but the Western Norway region (Fjord Norway) boasts the next two spots on the list, with the Sognefjord (203 km), and the Hardanger Fjord (179 km).

What unfolds as you travel Fjord Norway, is a fantastic story of water, with many chapters. The fjords were carved by a massive sheet of ice up to three kilometres thick that covered Northern Europe in a succession of ice ages. As you peer up at the towering mountains surrounding the Nærøyfjord, the narrowest fjord in the world, you can appreciate the immense power of those forces of nature.