Some creatures of the sky are equally at home beneath the surface, turning water into a second hunting ground. Their bodies are built for dual lives, with feathers or coverings that resist the chill and streamline their movement as they dive. While many animals skim the surface, these specialists plunge below, using wings or feet as paddles to pursue prey hidden from view. This remarkable shift from air to water sets them apart as masters of two realms.
Adaptations for underwater swimming vary widely. Some rely on powerful legs positioned far back on their bodies, turning each kick into efficient thrust. Others have evolved wings that function like flippers, allowing them to “fly” through the water with speed and precision. Even buoyancy is carefully managed—dense bones or partially wettable feathers reduce lift, helping them slip beneath the surface without struggle. These modifications make them among the most versatile hunters in nature.
The pursuit of food drives this behavior. Beneath the water, they hunt fish, crustaceans, squid, and other aquatic life. Some dive shallowly in lakes and rivers, grabbing plants or invertebrates, while others venture to astonishing depths in the open ocean. A few can remain submerged for minutes at a time, their bodies storing oxygen in ways that allow them to outlast the escape attempts of their prey. For them, every dive is a test of stamina and timing.
Geography also shapes the role of these underwater foragers. In icy polar waters, they rely on layers of fat and specialized plumage to stay warm during repeated dives. In temperate lakes and marshes, their diet shifts to whatever small creatures are abundant, from insects to amphibians. Along rocky coasts, they plunge into surf and currents, chasing schools of fish with the same determination they show in calmer waters. Their ability to adapt makes them vital parts of many ecosystems.
Birds That swim Under Water
Common Loon (Gavia immer)
The common loon is an expert diver, using its powerful legs set far back on its body to propel itself beneath the surface. With sharp, spear-like bills, they chase down fish with precision, often staying submerged for over a minute. Their bones are denser than those of most other birds, reducing buoyancy and allowing them to slip easily under the water. Found in northern lakes and coastal waters, they are iconic for their haunting calls as well as their diving prowess.
Pied-billed Grebe (Podilymbus podiceps)
This small but agile diver can compress its feathers to control buoyancy, letting it sink quietly beneath the surface without splashing. It hunts insects, crustaceans, and fish underwater, relying on quick paddling movements from its lobed toes. Rather than flying away from danger, it often disappears underwater and resurfaces at a distance. Its stealthy swimming abilities make it well adapted to freshwater ponds and marshes across the Americas.
Double-crested Cormorant (Phalacrocorax auritus)
Cormorants are streamlined swimmers with webbed feet and a flexible body ideal for chasing prey underwater. They use their hooked bills to snatch fish and can dive to depths exceeding 20 meters. Unlike ducks, their feathers are only partially waterproof, which reduces buoyancy but requires them to spread their wings to dry afterward. They thrive in coastal waters, rivers, and lakes, where they often hunt cooperatively in groups.
Emperor Penguin (Aptenodytes forsteri)
As the largest of all penguins, the emperor is built for extreme underwater performance. It can dive deeper than 500 meters and remain submerged for more than 20 minutes. Its streamlined body and flipper-like wings enable rapid swimming, while specialized hemoglobin allows efficient oxygen storage. Living in Antarctica, it pursues fish, squid, and krill beneath the ice, making it one of the most accomplished avian divers in the world.
Little Auk (Alle alle)
Also known as the dovekie, this small seabird uses rapid wingbeats underwater like a penguin, “flying” beneath the surface in search of plankton and small fish. It breeds in the Arctic and spends winters in the North Atlantic, where vast flocks forage at sea. Its compact body and fast swimming make it surprisingly efficient despite its size. The little auk demonstrates how even small birds can excel at underwater hunting in harsh environments.
Great Crested Grebe (Podiceps cristatus)
This elegant bird is known for its spectacular courtship displays on the water’s surface, but it is equally skilled below it. With sharp, pointed bills and strong legs, it dives gracefully in search of fish, insects, and amphibians. Its long neck provides extra reach underwater, while its streamlined body minimizes resistance. Found across Europe, Asia, Africa, and Australia, it thrives in freshwater lakes and large ponds.
Tufted Puffin (Fratercula cirrhata)
Despite their stocky appearance, puffins are agile underwater swimmers. They use their wings like flippers to “fly” through the water, chasing down fish such as sand eels. Their brightly colored bills, famous during breeding season, are also highly effective for carrying multiple fish at once. Puffins nest in coastal cliffs of the North Pacific, diving as deep as 60 meters to feed themselves and their young.
Common Murre (Uria aalge)
This seabird is an exceptional diver, often reaching depths of 100 meters in pursuit of fish. Like puffins, it uses its wings for propulsion underwater, moving with remarkable speed. Its narrow body reduces drag, while its high-energy metabolism fuels repeated dives throughout the day. Breeding colonies on rocky cliffs can number in the thousands, with adults commuting between sea and nest in constant cycles of underwater hunting.
African Penguin (Spheniscus demersus)
Native to the coasts of southern Africa, this penguin is adapted for rapid underwater swimming with flipper-like wings and streamlined bodies. It dives for sardines and anchovies, often working in groups to herd schools of fish. Its waterproof plumage and thick layer of fat provide insulation in cooler waters. Despite their playful surface behavior, these birds are serious and skilled hunters beneath the waves.
Brown Pelican (Pelecanus occidentalis)
While best known for plunge-diving from the air, brown pelicans are also strong swimmers beneath the surface. After hitting the water with remarkable accuracy, they often pursue fish underwater using their powerful webbed feet. Their expandable throat pouch allows them to scoop up prey and water, which they then drain before swallowing. Their combination of aerial diving and underwater swimming makes them versatile coastal hunters.
Gentoo Penguin (Pygoscelis papua)
Recognized by their bright orange beaks and white head markings, gentoos are the fastest swimmers among penguins, reaching speeds up to 36 km/h underwater. They use their strong flippers for propulsion and their tails for steering, darting after krill and fish with incredible agility. Found on sub-Antarctic islands, they can dive more than 200 meters deep and are capable of performing up to 500 dives per day during feeding periods.
Horned Grebe (Podiceps auritus)
This small grebe is instantly recognizable in breeding season with its striking golden “horns.” Beneath the water, it is an agile predator, diving after aquatic insects, crustaceans, and small fish. It uses lobed toes to propel itself, steering with precision while submerged. Found across North America and Eurasia, it thrives in shallow lakes and wetlands, where its diving skills help it exploit prey-rich environments.
Razorbill (Alca torda)
A close relative of the puffin, the razorbill uses rapid wingbeats underwater to chase down schooling fish. Its thick, black-and-white plumage streamlines its body, and its deep, laterally compressed bill helps it grip slippery prey. Capable of diving beyond 120 meters, it spends much of its life at sea in the North Atlantic. Colonies often nest on steep cliffs, where adults commute tirelessly between the open ocean and their young.
Magellanic Penguin (Spheniscus magellanicus)
Native to the coasts of Argentina and Chile, this penguin is a fast swimmer that hunts anchovies, squid, and other small sea creatures. It dives to depths of 50 meters, though it can go deeper when necessary, and uses its strong wings to “fly” through water. Seasonal migrations carry it far offshore, showing its endurance as both a surface and underwater traveler. Its adaptability helps it survive in varied marine conditions.
Red-throated Loon (Gavia stellata)
The smallest of the loons, this species is also among the most graceful divers. It forages in both freshwater and coastal marine habitats, pursuing fish with quick, efficient strokes. Its slender body and narrow bill reduce drag, allowing it to dart through water with minimal effort. In the breeding season, its red throat patch adds a splash of color to its otherwise gray and white plumage, but underwater it is all business.
Eurasian Coot (Fulica atra)
Though often seen dabbling at the surface, the Eurasian coot is also a strong diver. It plunges beneath the water to reach aquatic plants, roots, and small invertebrates. Its lobed toes act like paddles, providing excellent thrust in freshwater lakes and ponds. This adaptability allows it to feed on both vegetation and animals, making it one of the more versatile underwater foragers among non-seabirds.
King Penguin (Aptenodytes patagonicus)
Second in size only to the emperor penguin, this species is an accomplished deep diver, reaching depths of over 300 meters. Its torpedo-shaped body and flipper-driven propulsion make it exceptionally fast and efficient. Feeding primarily on lanternfish and squid, it can stay submerged for more than five minutes. Colonies numbering in the tens of thousands can be found on sub-Antarctic islands, where their diving skills support massive breeding populations.
European Shag (Gulosus aristotelis)
This coastal diver specializes in underwater hunting along rocky shores of Europe and North Africa. With slim bodies and strong, hooked bills, shags dive to depths of 45 meters in pursuit of fish. Their feathers absorb some water, decreasing buoyancy and allowing them to stay submerged longer. They often forage in small groups, herding schools of fish into shallows where capture is easier.
Black Guillemot (Cepphus grylle)
This striking seabird, with its black plumage and vivid red feet, is a swift underwater hunter. It uses its wings to “fly” through the water, diving down to catch fish and crustaceans along rocky coasts and Arctic seas. Unlike some seabirds, it prefers to forage alone or in pairs, darting around underwater rocks with impressive maneuverability. It is especially well adapted to cold, icy waters.
Adélie Penguin (Pygoscelis adeliae)
One of Antarctica’s most iconic species, the Adélie penguin is an energetic diver that can plunge to depths of around 175 meters. It feeds primarily on krill, which it captures in coordinated group dives. Its streamlined body and strong flippers allow for quick underwater movements, helping it evade predators as well as catch prey. These penguins are central to the Antarctic food web, linking the abundance of krill to larger marine predators.
Common Eider (Somateria mollissima)
This large sea duck is a specialist at diving for mollusks, particularly mussels, which it pries from the seafloor. Its down feathers are famously soft and insulating, protecting it in frigid northern waters. While not as deep-diving as penguins or murres, it is capable of staying submerged long enough to forage effectively. Found along Arctic and sub-Arctic coasts, it relies heavily on its underwater foraging to sustain large breeding colonies.