The world's largest algal bloom spans from the Caribbean to West Africa.

Satellite imagery of the massive seaweed blob in the Atlantic

Aerial photos of red tide off the Gulf Coast

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.

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.

To fight invasive species, some people have harvested them to produce useful materials that can be sold for a profit.

The seafloor contains hundreds of brine pools—underwater lakes that are many times saltier than the surrounding ocean and lethal to most marine creatures.

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

Plastic debris across the ocean aids the spread of invasive species

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

The world's largest garbage patch, explained

Explore a map of coral reefs around the world and the extent of coral bleaching.

How marine debris accumulates in giant garbage patches

While major oil spills result from accidental pipeline ruptures or damage to transportation vessels or rigs, as much as half the oil that reaches coastlines has naturally leaked from the seafloor.

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

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

Earth's oceans do mix, despite viral images and videos claiming to show boundaries between oceans that waters do not cross.

Algae produce about half of Earth's atmospheric oxygen and can capture carbon dioxide at rates up to 50 times faster than land-based plants.

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.

The Southern Ocean features the Antarctic Circumpolar Current—the largest ocean current on Earth—which encircles Antarctica and creates a unique biogeographical zone.

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.

While invasive species typically harm ecosystems by outcompeting native organisms for resources, some provide unexpected benefits, including new shelters, nesting habitats, and reduced environmental heat stress.

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.

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

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, contributing to their status as keystone species.

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

How salt, sunlight, and wind drive ocean currents

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

Elysia chlorotica is a sea slug that can photosynthesize, making it an animal with the defining ability of a plant.

El Niño makes the equatorial Pacific Ocean bluer than usual as high temperatures kill off microscopic plants that normally give the waters a green hue.

Invasive species can harm infrastructure and threaten human health

How a polluted New York City waterway created extremophiles hungry for 'black mayonnaise'

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

The harsh realities of the Great Pacific Garbage Patch

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.

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.

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.

How flooding the Dead Sea could help the climate

Some corals absorb harmful ultraviolet radiation and re-emit it as visible light, thereby protecting symbiotic algae within their tissues and providing them with energy for photosynthesis.

About 76% of global coral species are found in the Coral Triangle—a region spanning the waters of Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste.

It's always snowing in Earth's oceans, but marine snow is predominantly made of decaying organic material, not ice crystals.

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home.

The 1969 Santa Barbara oil spill galvanized the modern environmental movement

Watch a visualization of global ocean currents from NASA's Estimating the Circulation and Climate of the Ocean project.

The world's largest coral, as seen from space

25 million pounds of beads are distributed every Mardi Gras, leading to environmental concerns

By targeting a diverse range of sick and injured marine life, sharks—a type of predatory keystone species—help keep ocean gene pools healthy and promote biodiversity by keeping prey species in check.

From 2023 to 2025, coral reefs experienced their fourth global bleaching event and the largest such event through 2025.

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

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.