As of 2026, the Great Atlantic Sargassum Belt is the world's largest macroalgal bloom, with seaweed stretching from the Caribbean to West Africa.

Satellite imagery of the massive seaweed blob in the Atlantic

A belt of sargassum seaweed that stretches from the west coast of Africa to the Gulf of Mexico is the largest on record for March.

The world's largest species of marine algae is giant kelp, which can grow as much as two feet per day from depths of about 100 feet up to the ocean surface.

Aerial photos of red tide off the Gulf Coast

The toxic algae grows naturally in warmer oceans in small amounts and is typically harmless. With extended warm periods and unusually-high additions of nutrients from run-off, the algae blooms extensively, posing health risks to wildlife and humans...

Turning some invasive species into cash crops has helped control their spread

In Mexico, some companies are transforming sargassum seaweed blooms into paper, bricks, and shoes, while in Cambodia, water hyacinths are dried and woven into baskets, rugs, and other crafts. Lionfish and green crabs have been hunted for culinary dishes, with the latter also being used to make crab whiskey in New England.

Harmful algal blooms can occur in warm, nutrient-rich, stagnant waters and are often associated with the rapid reproduction of blue-green algae—a misnomer for cyanobacteria, not algae.

The ocean's ability to store carbon long-term is being hindered by marine heatwaves

More than 4,000 robotic floats with biogeochemical data sensors, including oxygen, pH, nitrate, suspended particles, chlorophyll, temperature, and conductivity, have been deployed as part of the Global Ocean Biogeochemical Array. They have identified changes to ecosystem structure affecting the ocean's ability to transport carbon from surface waters into the deep.

Plastic debris across the ocean aids the spread of invasive species

The durable, long-lasting material can serve as a platform for living organisms to latch onto and ride over vast distances. After the 2011 earthquake and tsunami in Japan, a large dock carrying 100 tons of living organisms native to Japan washed up on Oregon's coastline, confirming the ecological threat.

The world's largest garbage patch, explained

The Great Pacific Garbage Patch is the largest accumulation of ocean plastic in the world and is located between Hawaii and California. Scientists of The Ocean Cleanup Foundation have conducted the most extensive analysis ever of this area.

Scientists have collected critical minerals from ocean water using seaweed, a type of algae that leaves behind a mineral-rich powder called bio-ore after being processed into biofuels.

Despite being multicellular and photosynthetic, organisms such as kelp and sea moss are macroalgae, not plants, because they lack specialized roots and stems to pump water.

Alaska's Bristol Bay hosts the world's largest self-sustaining wild salmon runs

Nearly 50 million of the fish return to the area each year to spawn, sometimes in the same spot they were born. A journalist tracked the supply chain journey of one sockeye salmon from the sea to the customer's plate.

Molecules derived from algae can be found in foods such as ice cream, salad dressings, brownie mix, and gravies, as well as in products such as toothpaste, multivitamins, and egg substitutes.

Algae can capture carbon dioxide at rates up to 50 times faster than land-based plants and can be grown in tanks that use one-tenth the land footprint of terrestrial plants.

Whale falls—dead whales that have fallen to the ocean's floor—can provide enough food to spawn a local ecosystem of deep-sea organisms that lasts for decades.

Massive blooms of microscopic algae called dinoflagellates produce the neon blue light seen in glowing tides.

How marine debris accumulates in giant garbage patches

National Geographic breaks down everything you need to know about The Great Pacific Garbage Patch, along with pictures. The Great Pacific Garbage Patch is a collection of marine debris in the North Pacific Ocean. Marine debris is litter that ends up in the ocean, seas, and other large bodies of water.

Mangrove forests can store up to four times as much carbon as other forests and protect inland areas through complex root systems that absorb wave energy and hold mud and soil in place.

Climate change threatens coral reefs by disrupting the symbiotic relationship between corals and algae due to rising ocean temperatures.

Decommissioned oil rigs have been repurposed into artificial reefs that serve as nursery habitats for fish, corals, sponges, and other invertebrates in the decades since their installation.

Gulf nations produce about 40% of the world's desalinated water

According to a 2023 report, six Gulf states produced 1.9 trillion gallons of freshwater across more than 400 desalination plants along their coasts. These plants create water suitable for human consumption by boiling saltwater and collecting steam or using high-pressure pumps to push seawater through a filter that only allows water molecules through.

Oceans absorb 90% of warming from greenhouse gases

Oceans are providing increasingly more energy to power hurricane intensity. Current projections show rapid intensification is becoming more common, increasing the likelihood of Category 4 and 5 storms.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

The harsh realities of the Great Pacific Garbage Patch

Misleading images and narratives have caused the public to believe that the Great Pacific Garbage Patch is simply a large clump of floating trash in the ocean. Instead, a more apt description would paint it as a dispersed "soup of microplastics" that severely impacts marine life and the fishing industry. Read for a greater understanding of how the GPGP came to be, and the measures that need to be taken for a cleanup.

The Southern Ocean's powerful circular current isolates organisms in its environment

The spiralling current churns up nutrients across the frigid waters, leading to the evolution of fantastical organisms, including century-old starfish and colossal squid, and unique adaptations, including the icefish's clear blood and organic antifreeze, over the past 30 million years.

Some algae have helped remove microplastics from water after being bioengineered to clump together with these contaminants, forming an easily collectible microplastic-algae sludge.

Watch the destructive force of bottom trawling on marine ecosystems

Bottom trawling is a fishing method where a net is dragged along the seafloor to catch a species of interest. The process produces as much carbon dioxide yearly as global aviation and leaves trails of destruction large enough to be seen in space.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

The cells of spotted salamander embryos and early-stage larvae harbor algae that support embryonic development by increasing oxygen levels and removing waste.

View a gallery of animals found on abyssal plains, hydrothermal vents, seamounts, and other deep-sea habitats.

How flooding the Dead Sea could help the climate

There are many dead zones in the world with low elevation and very little rainfall that provide little to no benefits to the ecosystem or climate. This digestible, thorough article explains how piping in nearby water to flood these areas could...

The Amazon rainforest is considered the 'lungs of the Earth,' but it contributes less than a quarter of the oxygen of phytoplankton—microscopic plants, algae, and bacteria capable of photosynthesis.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

Feeding grazing cattle seaweed cut their methane emissions by almost 40%

The largest share of the 12% of global greenhouse gas emissions from livestock comes from methane released when cows burp. A study found that introducing a seaweed supplement in pellet form significantly reduced these emissions without affecting cattle's health or weight.

The 1969 Santa Barbara oil spill galvanized the modern environmental movement

In January 1969, an oil platform off the coast of Santa Barbara ruptured, releasing roughly 3 million gallons of crude into the Pacific. The spill killed over 10,000 seabirds, dolphins, and seals, coating 35 miles of coastline.

The world's maritime traffic in real-time

More than 50,000 ships are sailing the high seas on any given day, representing the highest volume pathway for international trade. This real-time traffic provides a visual impression of the scale of ocean-bound commerce.

How salt, sunlight, and wind drive ocean currents

The Atlantic Meridional Overturning Circulation plays a critical role in regulating earth's climate, but is threatened by climate change. Explore the effects of temperature, density, and salinity on ocean currents in this 13-minute PBS video.

What we know about the mysterious colossal squid

The colossal squid, the world's largest invertebrate, remained hidden from human discovery until nearly a century ago. Explore the world of the enormous and mysterious creature, including its features, habitat, and scientific significance. You can even plan a visit to the Museum of New Zealand Te Papa Tongarewa and marvel at a real-life display.

The ‘humongous fungus’ may be the largest organism on Earth at more than 2,300 acres

Discovered in 1988, when it was only covering 400 acres, this massive colony of Armillaria ostoyae, based in Oregon, has taken hold among the tree roots of the Malheur National Forest. It consists of a vast network of unique long black filaments of fungal tissue called rhizomorphs that grow under the soil and infect tree roots, nourishing the fungus but killing the trees. Researchers believe this fungal growth dates back more than 8,000 years and currently weighs approximately 35,000 tons.

View some of the most invasive species in US waters

Introduced in the late 1600s from Eastern Asia, the goldfish is considered the first invasive fish in North America. The venomous lionfish is safe to consume, but catching it is complicated by its reluctance to respond to hook-and-line-style fishing attempts.

What makes the world's biggest waves?

Some of the world’s biggest waves, routinely reaching 100 feet high, are formed near the town of Nazaré, Portugal. But what makes this area so prone to massive swells? While a number of factors are involved, the key feature is the Nazaré Canyon,...

The world's largest waterfall is in the ocean

In the Denmark Strait between Greenland and Iceland, a series of cataracts descend from 2,000 to 10,000 feet beneath the surface. The underwater waterfall is possible because cold water is denser than warm water and quickly sinks in the region.

Track individual sharks around the world in real time

OCEARCH provides essential data on shark populations and marine ecosystems to support broader conservation efforts. Foster your understanding of marine ecosystems by exploring different species and their movement.

A submarine canyon helps produce the biggest ocean waves in the world

Off the shores of Nazaré, Portugal, the canyon is nearly three times as deep as the Grand Canyon in places. This creates a rare convergence of fast and slow swells that erupt into towering walls of water over 100 feet high.

The floating homes of Holland

Floating communities like Schoonschip in Amsterdam are offering a novel approach to combat climate change-induced flooding. With sea levels rising and storms becoming more intense, these floating neighborhoods are providing a sustainable flood defense solution. Learn how they work here.

The history of deep-sea mining and its governance by the International Seabed Authority

The British HMS Challenger research vessel identified metal-rich seafloor rocks between Hawaii and Mexico in the 1870s, but rules governing which nations control which parts of the ocean were not established until 1958 by the UN. It later established the ISA to oversee mineral-related operations in international waters.

Why is sea level rising?

Rising global sea level is one of the most commonly cited consequences of climate change, but it’s often unclear how it might affect people living on the coasts. Read this explanation of why global sea level is rising and why sea level rise happens at different rates in different locations.

The Arctic is greening from rising temperatures

This one-minute video summarizes a new study that used satellite data to look at plant life across the entire Arctic area for the first time. It found that from 1985 to 2016, 38% of the areas studied—including parts of Alaska, Canada, and...

Visualizing changes in ocean temperatures between 2016 and 2020

How much does the temperature of the sea change in a given year? This visualization helps illustrate the changes by showing sea surface temperature data from January 2016 through March 2020. Sea surface temperature, which refers to water temperature at the sea's surface, plays a significant role in climate and weather.

As of 2025, China has been awarded the most deep-sea mining contracts by the ISA

The International Seabed Authority—established by the 1982 United Nations Convention on the Law of the Sea—grants 15-year contracts for governments and private companies to legally search for minerals and test seabed mining technologies. China is already the global leader in the processing and refining of critical minerals.

Why deep-sea mining companies may begin extraction without global guidelines

International Seabed Authority negotiators have spent over a decade drafting regulations that all countries would have to follow before collecting minerals from the seabed. Because deadlines to finalize these agreements have been missed, some entities have discussed unsanctioned mining, despite about three dozen ISA countries calling for a pause on activity and automakers and tech firms pledging they will not use seabed minerals.