Beneath the waves lies a hidden frontier: the continental shelf. This submerged plain shapes coastlines and supports countless ecosystems. But what exactly is the continental shelf? Why is it important? And why should we explore this underwater realm?

What is the continental shelf?

The continental shelf is the submerged perimeter of continental landmass that extends beneath the ocean, sloping towards a steep drop known as the continental slope.

Picture an iceberg floating out in the open ocean. You can see and touch the part of the iceberg above the surface of the water. But extending below the ocean and outwards is a hidden mass of ice.

The hidden portion of the iceberg is the continental shelf in this analogy, extending out from the visible land in relatively shallow water.

Continental shelves were formed over millions of years through the combination of tectonic activity, sediment deposition, and changes in sea levels during glacial periods.

But more than a geographical feature, the continental shelf is a critically important area within the ocean.

Where are continental shelves found?

Continental shelves are found fringing nearly every continent, typically at maximum depths of 50 to 200 meters, although they can vary dramatically in width and character depending on location.

Some shelves, such as those you find off the eastern coast of North America and northern Europe, are broad and gently sloping, providing a vast area of shallow marine habitat.

By contrast, the shelves along the Pacific coasts of North and South America are much narrower, with the seabed dropping away steeply not far from shore.


International law and territorial waters

Beyond its geological and ecological significance, the continental shelf plays a crucial role in international law and global politics. The boundaries and rights associated with continental shelves are defined by legal frameworks such as the United Nations Convention on the Law of the Sea (UNCLOS). These legal definitions determine which country has the right to explore and take natural resources like oil, gas, and minerals from the seabed.

Understandably, the continental shelf is often a prominent feature of geopolitical negotiations and disputes, shaping the economic and strategic interests of coastal nations.

Why do continental shelves matter?

The continental shelf is important because it is essential for both marine ecosystems and human economic activities.

The surface area of the world’s continental shelves makes up just 8% of the ocean’s surface.

But this small proportion of the ocean has a disproportionate impact on the planet’s health and our daily lives.

The relatively shallow waters of continental shelves let sunlight through to the seabed, promoting the growth of plankton, which forms a base for the marine food web.

Continental shelves are rich in life because of this. They serve as habitats for an astonishingly wide variety of marine species. They provide ideal conditions for the growth of coral reefs, kelp forests, and seagrass meadows. These in turn provide a home for a diverse range of marine life, from tiny plankton to large fish and marine mammals.

This biodiversity is crucial for keeping ecological balance and resilience, as well as supporting the commercial fishing industry, which many communities rely on.

Continental shelves have significant economic importance. They are typically rich in natural resources and play a role in supporting multiple industries, including global energy production, mineral supply, fisheries, and tourism.

It’s on continental shelves that you will find a range of critical subsea infrastructure, including undersea cables and pipelines that support the global economy.

For these reasons, it’s critical to understand and conserve the continental shelf.

Threats to continental shelves

Continental shelves face threats from a range of human activities and environmental pressures.

Overfishing is a major concern, as intense harvesting of marine life depletes fish populations, and disrupts delicate habitats like coral reefs and seagrass meadows.

Coastal development and pollution such as sewage discharge and plastic waste can harm marine organisms and impact ecosystem health.

Climate change represents another significant threat to continental shelves as rising ocean temperatures and acidification negatively affect marine life and ocean health.

How does DEEP’s work relate to the continental shelf and its health?

We need to explore the continental shelf to better understand its importance to the planet’s health and learn how to best conserve it.

In addition, exploring the shelf will advance science and lead to new discoveries with far-reaching implications.

There are different ways we can access the ocean to explore and research it.

Remote sensing uses advanced technologies to collect and analyze data underwater without direct physical contact. This might mean an autonomous underwater vehicle (AUV) mapping the seafloor to produce a detailed visualisation of the features of the seabed.

Submersibles (manned or unmanned) and ROVs (remotely operated vehicles) allow scientists to directly observe and collect data with sensors and manipulator arms.

But this technology is typically best suited and most economically viable for deep-ocean exploration. For example, the submersible Alvin, operated by Woods Hole Oceanographic Institution, has been instrumental in deep-sea research, reaching depths of up to 6,500 meters.

When exploring the continental shelf, there are huge benefits to having a human presence. Diving plays a crucial role in the research and exploration of continental shelves by allowing scientists to directly observe and interact with underwater environments.

However, the depth range between 50 and 200 meters (typical shelf depths), sometimes referred to as “the research blind spot”, is challenging to explore using conventional diving methods.

Traditional surface diving techniques limit the time researchers can spend underwater, especially at greater depths. However, advanced diving technologies, such as saturation diving and the use of subsea human habitats, allow scientists to stay underwater for extended periods. This extended bottom time is crucial for conducting comprehensive studies and capturing long-term data.

Subsea human habitats, such as DEEP's Sentinel, allow researchers to stay submerged for 28+ days. This extended presence eliminates the need for repeated resurfacing and decompression, significantly increasing productive bottom time and accelerating scientific discovery. Learn about the different types of scientific research that can be conducted from a subsea human habitat here.

Follow the mission

DEEP’s mission is to make humans aquatic. With our next-generation subsea human habitats, we are enabling a new era of exploration throughout the continental shelf.

Follow our progress by following us on social media @deepengineered and visiting our Newsroom.

[1]The U.S. Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA) both estimate the continental shelf makes up about 7–8% of the total area of the ocean.