Fjords are Underwater U-Shaped Glacial Valleys

Naeroyfjord Fjord
A passenger liner sails along the Naeroyfjord in Norway. The Naeroyfjord is a UNESCO World Heritage site. Arnulf Husmo/Getty Images

A fjord is a narrow, high-walled, and very long submerged glacial valley. Fjords are formed when a descending glacier carves a U-shaped valley into the bedrock. Often, the force of the descending glacier carving into the bedrock is so strong that fjords tend to be deeper than the oceans that they empty into. Simply put, like river systems, fjords are extravagant previously frozen estuary systems.


Skerry arrays can act as a shield from violent ocean currents. Although at times they can be extremely difficult for sailors to navigate around, skerries provide a sheltered passage of calm and gentle waters for trading ships traveling along the coastline.

Fjords Around the World

Puget Sound is located in the state of Washington and is an extensive fjord system of flooded glacial valleys. Second only to the Chesapeake Bay, Puget Sound is the second largest estuary system in the United States.

Nutrient Circulation in Fjords

Freshwater high in dissolved oxygen drains into the Sound from mountain streams, and exist high in the water column because of their relatively low density. This causes tidal inflow of cold, nutrient-rich water deep in the water column from the ocean.

Nutrient circulation is also heavily based on wind direction. Winds from the north coerce cold, dense, seawater to enter the Sound through the Strait of Juan de Fuca. This water is extremely oxygen poor but rich in nutrients.

Conversely, wind from the south causes surface water in the Sound to push against the shore, dragging in surface water from the adjacent ocean. This water is rich in oxygen but relatively nutrient poor.

Unique Biogeographical Patterns in Fjords

These nutritious waters encourage unique and interesting fauna to make their home in fjords. For example, in recent years coral reefs were discovered in the extremely dark, cold, and deep waters of Norwegian fjords. These ancient reefs are posited to be some of the largest in the entire world. These cold-water Norwegian reefs support life ranging from microscopic algae and corals to larger animals such as sea anemones and fish, including several species of sharks, all in almost complete darkness. These reefs are believed to be one reason why Norway's waters are such rich fishing grounds.

In combination with the calm waters and many fishes found in fjords, fjords serve as a haven for several species of whales. These whales, for example the Orca or "killer whale" use fjords as important feeding grounds during their yearly migration through the world's oceans.

Fjords are statuesque and dazzling reminders of the glacial fingers that carved deep into the land, connecting mountains to sea where temperatures during the last great ice age were low enough to accommodate glaciers. They continue to amaze and enchant us, obvious from Norway's bustling fjord ecotourism industry. If an entire ancient coral reef was only just discovered less than two decades ago at the bottom of a Norwegian fjord, than what else lies below in these cold waters shrouded in mystery?