The Emperor penguin is the largest penguin species, standing 110–130 cm tall and weighing 30–40 kg. Emperors are the deepest-diving birds on Earth, routinely diving 300–500 metres, with recorded dives exceeding 500 metres, and remaining underwater for over 20 minutes. They cruise underwater at around 6–9 km/h, accelerating when hunting fish and squid beneath the sea ice. Their ability to slow their heart rate and redirect oxygen to vital organs allows them to survive dives that push the limits of vertebrate physiology.

The King penguin is slightly smaller than the emperor, reaching 90–100 cm and weighing 13–18 kg. King penguins are powerful divers, commonly reaching depths of 100–300 metres and remaining submerged for up to 10 minutes. Their prolonged breeding cycle—lasting more than a year—means colonies often contain eggs, chicks, and moulting adults all at once, creating the dense, bustling scenes typical of South Georgia.

The Gentoo penguin is one of the fastest underwater swimmers of all penguins, reaching speeds of up to 36 km/h in short bursts. Adults stand around 75–90 cm tall and weigh 5–8 kg. Gentoos are relatively shallow divers compared to larger species, typically diving 50–200 metres, and are often seen porpoising through the water near shore.

The Chinstrap penguin is a medium-sized penguin, weighing 3–5 kg, with a highly energetic and vocal nature. Chinstraps usually dive to 70–150 metres and feed almost exclusively on krill. Their dense colonies—often numbering in the hundreds of thousands—are among the loudest and most frenetic in Antarctica.

The Adélie penguin is a compact, robust species weighing 4–6 kg. Adélies typically dive to 50–175 metres and are strongly associated with sea ice, using it as a platform for resting and feeding. Their reliance on ice makes them a key indicator species for environmental change in Antarctica.

The Macaroni penguin weighs 5–6 kg and is one of the most numerous penguins on the planet. They are efficient foragers, diving 50–200 metres, and spend much of their lives at sea. On land, their steep, rocky nesting sites and constant movement give colonies a chaotic energy.

The Southern rockhopper penguin is small—around 55 cm tall and 2–3.5 kg—but extraordinarily agile. Rather than sliding, rockhoppers bound up cliffs using powerful legs. They typically dive 30–100 metres and are among the most characterful penguins encountered on South Georgia.

The Southern elephant seal is the largest seal species, with adult males reaching 5–6 metres in length and weighing up to 4,000 kg. Elephant seals are exceptional divers, routinely diving 500–1,000 metres and capable of dives exceeding 2,000 metres, remaining underwater for up to two hours. Despite their immense size, they spend over 80% of their lives at sea, surfacing only briefly between dives.

The Antarctic fur seal is far smaller and more agile, weighing 25–200 kg depending on sex. Fur seals typically dive 20–200 metres and are fast, acrobatic swimmers. On land, they are famously territorial, especially during breeding season, making them entertaining—but unpredictable—neighbours to penguin colonies.

The Leopard seal is Antarctica’s apex seal predator, reaching 3–3.6 metres in length and weighing up to 600 kg. Leopard seals can dive over 300 metres and are capable of sudden bursts of speed when hunting penguins near ice edges. Solitary and intelligent, they are as formidable as they are fascinating.

The Weddell seal weighs 400–600 kg and is known for its calm disposition and haunting underwater vocalisations. Weddells typically dive 200–600 metres and can remain submerged for over an hour, maintaining breathing holes in sea ice with their teeth.

The Humpback whale reaches lengths of 12–16 metres and weighs up to 40 tonnes. In Antarctic waters, humpbacks gorge on krill, diving 100–200 metres repeatedly throughout the day. Their long pectoral fins and surface behaviours—breaching, tail slapping—make them among the most recognisable whales.