Denmark Strait cataract underwater waterfall

The biggest waterfall in the world is underwater. It’s located between Iceland and Greenland. This waterfall, called the Denmark Strait Cataract, is over three kilometers high and has a flow of cold, dense water of over three million cubic meters per second. This huge current starts in the Arctic, where the surface water cools, gains density, and sinks. Then, it makes its way to lower latitudes, following the topography of the seabed. The submarine relief of the Denmark Strait makes this bottom current speed up and overflow in the form of an underwater waterfall until it reaches the great troughs of the northern Atlantic Ocean.

This event is important for the Atlantic thermohaline circulation, which affects the global climate. It’s also key to the functioning of the deep-sea ecosystems in the area. Scientists have studied this dense water overflow, but there are still important things that they don’t know. These things will be studied during the FAR-DWO oceanographic campaign, which will take place from July 19 to August 12. The research will be done aboard the oceanographic ship Sarmiento de Gamboa, and it will be led by Professors David Amblàs and Anna Sanchez-Vidal from the Consolidated Research Group on Marine Geosciences of the Faculty of Earth Sciences of the University of Barcelona (GRCGM-UB).

Exploring the lesser-known side of the Denmark Strait undersea waterfall

David Amblàs and Anna Sanchez-Vidal, members of the Department of Earth and Ocean Dynamics at UB, say that the large underwater waterfall has been studied before, but FAR-DWO aims to explore unknown aspects. The study will focus on its ability to transport sediments, alter relief, and how topography affects its propagation. FAR-DWO will analyze hydrographic and sedimentological variability by sampling and observing the water column and sediment. Two instrumented lines will be deployed at great depth and record current information for a year. The data will be recovered in September 2024.

A phenomenon described extensively and pioneeringly in the north of the Catalan coast

Underwater waterfalls are one of the most interesting things in the study of oceans. Scientists didn’t know how they affected the seafloor until a group of researchers from GRCGM-UB wrote about them in a scientific paper in 2006. Since then, the GRCGM-UB has been a leader in studying these waterfalls and uses special instruments like sediment traps, current meters, and temperature sensors. These waterfalls happen a lot in the Arctic and Antarctic regions. These areas are important because they produce most of the dense water in the ocean, which flows into the deep parts of the ocean. David Amblàs says it is like a heart pumping cold water into the deep ocean.

How does climate change affect undersea waterfalls?

Submarine waterfalls are being affected by global change, and scientists have noticed this in several areas. For example, the number of tramontane days in winter has decreased in the Gulf of Lion and north of the Catalan coast, causing a weakening of this oceanographic process. This is important because it helps regulate the climate and has a significant impact on deep ecosystems.

In polar areas, there is more freshwater and less sea ice formation, which means less dense water moving towards lower latitudes. This affects the global ocean circulation and is a concern for scientists.

Image Credits

In-Article Image Credits

Location of the Denmark Strait via Wikimedia Commons with usage type - Creative Commons License. August 1, 2023
the Denmark Strait, southward-flowing frigid water from the Nordic Seas meets warmer water from the Irminger Sea via NOAA with usage type - Public Domain
Denmark Strait cataract underwater waterfall via GRCGM-UB with usage type - News Release Media