Ten Things You Didn’t Know About Kelp

July 12, 2025

Cover image: Taylor Griffith

Kelp forests are some of the most dynamic and productive ecosystems on the planet, but many people don’t dip below the canopy to find out just how incredible they really are. From record-breaking growth rates to surprising uses spanning food, art, and innovation, here are ten things about kelp you might not know, as well as what you can do to help the kelp! 

1. Kelp forests are the largest marine habitat on Earth

Kelp forests cover more than one-third of the world’s coastlines, stretching across the shorelines of 21 countries on each continent except Antarctica. From the fjords of Norway to the rocky shores of New Zealand, these underwater forests thrive in cold, nutrient-rich waters where they form the foundation of nearshore marine ecosystems. Despite their global reach, kelp forests often remain hidden beneath the waves—out of sight, and too often, out of mind.

2. Kelps are champion growers

Giant kelp (Macrocystis pyrifera) is reported to grow up to 18 inches (45 centimeters) per day in ideal conditions, making them the second fastest-growing organisms on the planet, just behind certain species of tropical bamboo. Under the right conditions, canopy-forming kelps like giant kelp can reach towering heights of over 150 feet (45 meters), stretching from the seafloor all the way to the surface. Their rapid growth fuels the incredible productivity of kelp forests and supports the diverse life that depends on them.

3. Kelp forests are home to hundreds of species

These underwater forests provide food and shelter for an incredible diversity of marine life! From tiny snails and sea stars to larger animals like sea otters, seals, and finfish, kelp forests support both resident and migratory species and form the ecological backbone of many temperate coastal zones. Some animals depend on kelp directly for survival, while others rely on the structure it creates for feeding, breeding, and protection from predators.

4. There are many species of kelp

“Kelp” isn’t a single species, but a broad term for large brown algae, most of which fall in the order Laminariales. There are dozens of different species across the globe. Some kelp species, like giant kelp and bull kelp (Nereocystis luetkeana), grow tall and form dense canopies, while others, like winged kelp (Alaria marginata) and stalked kelp (Pterygophora californica) don’t grow as tall. Just like a forest on land isn’t composed only of the tallest trees, there are plenty of species in the understory that create important habitats closer to the ground. 

5. Kelp forests are under threat

Like coral reefs, kelp forests are among the marine ecosystems most vulnerable to climate change. Rising ocean temperatures and marine heatwaves have caused cascading impacts. In areas like Northern California and Tasmania, the marine heatwaves triggered overgrazing by native species of sea urchins which have led to the widespread loss of kelp canopy in the span of just a few years, replaced by barren seascapes that struggle to recover.

6. You’ve probably eaten kelp, even without realizing it

Kelp is a staple in many traditional cuisines—particularly across East Asia, where it’s used in soups, broths, and seaweed snacks. But it also appears in everyday products like ice cream, salad dressing, and toothpaste, thanks to alginates—a natural thickening agent derived from brown algae. 

7. Kelp inspires artists around the world

The majesty of kelp forests have sparked the imagination of artists around the world working in mediums from photography, sculpture, textiles, and ceramic to public installations. Ask any diver on the west coast of North America about the “kelp cathedral” and watch their eyes light up. Kelp-centric art is a powerful tool for education and advocacy that connects audiences emotionally with the ocean, and makes the invisible visible. 

8. Kelp forests are underwater nurseries

Kelp forests serve as important habitat for the young of many species of fish, crustaceans, and invertebrates. Their dense stands can help provide shelter from predators and strong currents, giving young marine life a safe place to grow. 

9. Kelp forests protect coastlines 

Healthy kelp forests can act as natural physical barriers to protect coastlines from erosion. By buffering the impact of waves and storms on the coast, they can help to slow coastal erosion, providing protection to both natural shoreline habitats and human communities.  

10. You can help the kelp!

Whether you live near the ocean or far from it, there are ways to support kelp forests. Warming oceans are the biggest threat to kelp forests worldwide – so any action you take that fights climate change is also one that helps the kelp. You can also directly support organizations worldwide working on kelp research and restoration. And, you can spread the word, as raising awareness is one of the most powerful tools we have to protect these extraordinary ecosystems.

Kelp forests are extraordinary—not only for what they are, but for what they make possible. They support biodiversity, inspire artists, and are woven into cultural traditions and coastal economies worldwide.

At Mission Blue, kelp is a priority. With the Mission Blue Kelp Initiative, we’re supporting research, protection, and restoration of kelp ecosystems in Hope Spots around the world. Today, 32 of our more than 160 Hope Spots include kelp forests, from the rugged fjords of Northeast Iceland to the Humboldt Archipelago in Chile and the dynamic coastline of Northern California. This year, we’re supporting four projects around the world where scientists, divers, artists, and community leaders are working to better understand and protect these critical ecosystems.

There’s still much to learn—and much to protect. But by recognizing the beauty and value of kelp forests, and supporting the people and projects working to sustain them, we can help ensure that these underwater forests continue to thrive for generations to come.

Learn more about kelp, and the work of Mission Blue Kelp Initiative, with the following articles:

Kelp 101: What Are Kelp Forests, and Why Do They Matter?

The Mission Blue Kelp Initiative: A Hope Spot Partnership for Kelp Protection

Hope Beneath the Waves: A Week with the Global Kelp Community in Victoria, Canada

5 Hope Spots You Might Not Know Have Kelp Forests

 

References:

Eger, Aaron M., McHugh, Tristin A., Eddy, Norah, Vergés, Adriana (Editors). State of the World’s Kelp Forests V1.0. Kelp Forest Alliance, Sydney, Australia. 

Eger, A., Aguirre, J.D., Altamirano, M. et al. The Kelp Forest Challenge: A collaborative global movement to protect and restore 4 million hectares of kelp forests. J Appl Phycol 36, 951–964 (2024).

Kelp Forest Alliance. 5 Reasons to Protect Kelp: The West Coast’s Powerhouse Marine Algae.
The Nature Conservancy and Kelp Watch. TNC Kelp Report Card 2024.

Iselin, Josie and Leuschel, Marianna. The Mysterious World of Bull Kelp: A Resource for Bull Kelp Science and Stewardship.