Island

Not all islands are "ocean-made": many are continental fragments that were once connected to a mainland (e.g., Britain was linked to Europe during the last ice age).

Some islands have freshwater on top of seawater: rain can form a floating "freshwater lens" underground, even on low coral atolls.

Islands can contain "islands within islands": an island can have a lake, with an island in that lake, and sometimes even another lake on that inner island.

The shoreline-to-interior gradient can be extreme: salty sea spray and wind can stunt coastal forests, while lush, taller vegetation thrives just a short distance inland.

Being surrounded by water doesn't guarantee mild weather-mountainous islands can create their own rain shadows, producing deserts or very dry zones right next to wet forests.

Isolation can make animals lose defenses: many island species evolved without predators and became flightless, tame, or unusually bold-until new predators arrived.

Islands don't always shrink with rising seas: some sandy reef islands can naturally shift position, rebuild after storms, or even grow in area as sediments move around.

Volcanic islands can appear (and vanish) quickly-eruptions can create brand-new land, but waves may erode it back below sea level in years or decades.

Maritime influence can amplify cloud and fog: "cloud forests" often form on island mountains where moist ocean air is forced upward, creating ecosystems that wouldn't exist at the same latitude inland.

Island size isn't the whole story for biodiversity: distance from other landmasses strongly controls which species arrive, a core idea of island biogeography.

Greenland is the world's largest island (and it's so big it spans several climate zones), while Australia is classified as a continent rather than an island.

New Guinea is the world's second-largest island and contains one of the highest island peaks on Earth: Puncak Jaya (4,884 m / 16,024 ft), the highest point on any island.

Manitoulin Island (Lake Huron, Canada) is the largest island in a freshwater lake in the world-and it even contains lakes with their own islands.

Bananal Island (Brazil) is widely cited as the world's largest river island, formed by the split channels of the Araguaia River.

The Netherlands' Flevopolder is generally recognized as the world's largest artificial island (a reclaimed polder surrounded by lakes).

Tristan da Cunha is often described as the most remote inhabited island group on Earth-its nearest inhabited neighbor is well over 2,000 km away.

Indonesia is the world's largest archipelagic country, with thousands of islands spread across a vast tropical ocean corridor.

Iceland is the world's largest island created primarily by volcanic activity above sea level, sitting astride the Mid-Atlantic Ridge.