The Coldest Sea on Earth: The Weddell Sea

Antarctica's Frigid Southern Ocean Marginal Sea

The Weddell Sea claims the title of world's coldest sea, with unique characteristics that create its extreme environment.

Key Facts

• Location: Southern Ocean, off Antarctica's coast (Queen Maud Land to Antarctic Peninsula)
• Average Temperature: -1.8°C (28.8°F) — at seawater's freezing point
• Ice Cover: Perennial sea ice covers most of the sea year-round
• Size: ~2.8 million km²
• Depth: Up to 5,000+ meters

Why So Cold?

• Antarctic Coastal Current: Circulates frigid water
• Ice Shelf Interaction: Massive Filchner-Ronne Ice Shelf cools water from below
• Deep Water Formation: Dense, cold, saline water sinks, driving global thermohaline circulation
• Limited Solar Input: High latitude, months of polar night

Thriving Despite Extremes

The Weddell Sea supports remarkable biodiversity adapted to freezing conditions:

• Marine mammals: Weddell seals, crabeater seals, leopard seals, whales
• Birds: Emperor penguins, Adélie penguins, petrels, skuas
• Unique fauna: Antarctic krill (keystone species), icefish (antifreeze proteins), giant sea spiders

Scientific Importance

Key site for climate research—Weddell Sea Bottom Water formation drives global ocean circulation. Proposed as a massive Marine Protected Area.