Third Order Islands

The world has a lot of islands. There are about 900,000 official islands in the world and hundreds of thousands of unnamed islands.

In geographical terms, an island is any piece of land that is completely surrounded by water. Islands come in all sizes and shapes. There are landmasses completely surrounded on all sides that they aren’t technically islands but are continents — Australia is the most prominent example.

The largest island in the world that isn’t classified as a continental landmass is Greenland with an area of 822,700 square miles (2,130,800 kilometers). On the flip side, the smallest islands, like Landsat Island, are tiny rocks that jut up above the surface of the water.

In between these two extremes of areas are most islands. These islands can be quite complex geographically. One area of classification among islands is their order.

What are recursive islands?

Recursive islands are islands that contain bodies of waters such as lakes or ponds that have smaller islands in those bodies of water. This creates a nested or “recursive” pattern of islands within islands. It’s like a nesting doll but with islands.

What causes recursive islands to form?

The formation of lakes on islands requires specific geographical and climatic conditions. Often recursive islands are found in areas where the landscape has been formed by the effects of glacial movement. Glacial retreat leaves behind thousands of depressions that fill up with meltwater and rainfall.

Another geographic phenomenon that creates recursive islands is the collapse of volcanoes which forms a depression known as a caldera. The caldera is then filled in by water, create a lake around the remnant peak.

Understanding the Orders of Islands

Diagram of the orders of islands

There are three orders of islands: first order island, second order island, and third order island.

First Order Island

This is a piece of land surrounded by a body of water.

Second Order Island

If an island has a lake and there is another piece of land within that lake, that island is a second order island. This is popularly called “island in a lake on an island in a lake” or “island in a lake on an island in a sea or ocean” or a sub-sub-island.

Third Order Island

Should that island in a lake on an island also have a lake that has another island, this is a third order island. These islands are called “island in a lake on an island in a lake on an island in a lake” or “island in a lake on an island in a lake on an island in a sea or ocean.” A shorter way of referring to this type of an island is a  “sub-sub-sub-island.”

World’s largest third order island

The largest third order island is an unnamed island found on Victoria Island in Canada’s Nunavut Territory. Victoria Island, one of over 36,000 islands in the Canadian Arctic Archipelago, is the the eighth-largest island in the world. Victoria Island contains an unnamed seahorse-shaped island that sits within a lake. That seahorse-shaped island also contains a lake. And within that lake lies a third order island that measures about 1,000 feet (300 meters) from east to west.

In 2007, island geographer Josh Calder was the first person to discover that this particular island in a lake on an island in a lake on an island is the world’s largest third order island after painstakingly reviewing Google Maps.

The third order island that disappeared and reemerged

Vulcan Point in the Philippines is one of the most famous of the “island in a lake on an island in a lake on an island.” Vulcan Point is a remnant of the old crater floor that juts out near the middle of Main Crater Lake on Volcano Island which lies in Taal Lake on the Luzon, the largest island in the Philippines.

In 2020, a volcanic eruption temporarily dried out Main Crater Lake. Taal Volcano eruption on January 12, 2020 and blanketed the entirety of Volcano Island in ash and evaporated the water that was in Main Crater Lake.

Rainfall has since refilled the lake, allowing Vulcan Point to once again become a third order island.

More island geography

• The First Newly Formed Island to Survive in the Satellite Era
• The Map Myth of Bermeja Island
• What is the Largest Island in the Pacific Ocean?