A recursive island or lake is an

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

or a

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

that lies within a lake or an island. For the purposes of defining

recursion Recursion (adjective: ''recursive'') occurs when a thing is defined in terms of itself or of its type. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in mathemati ...

, small continental land masses such as

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

count as islands, while large continental land masses do not. Islands found within lakes in these countries are often recursive islands because the lake itself is located on an island.

Recursive islands

Islands in lakes

Only a few notable examples are given.

Islands in lakes on islands

There are nearly 1,000 islands in lakes on islands in Finland alone.

Islands in lakes on islands in lakes

Islands in lakes on islands in lakes on islands

Nameless isle within Victoria Island in Nunavut Territory in Canada

Until 2020,

Vulcan Point Taal Volcano Main Crater Lake (; or simply Main Crater Lake), historically known as Yellow Lake, is a lake inside the main crater of Taal Volcano. The origin of the lake is uncertain but is thought to have formed by rainwater. The lake briefly d ...

was an island that existed in Main Crater Lake on Volcano Island in

Lake Taal Taal Lake ( tl, Lawa ng Taal, ), formerly known as Bombón Lake, is a freshwater caldera lake in the province of Batangas, on the island of Luzon in the Philippines. The lake fills Taal Volcano, a large volcanic caldera formed by very large e ...

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...

in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

. Main Crater Lake evaporated during the 2020 Taal Volcano eruption, but the water in

Taal Lake Taal Lake ( tl, Lawa ng Taal, ), formerly known as Bombón Lake, is a freshwater caldera lake in the province of Batangas, on the island of Luzon in the Philippines. The lake fills Taal Volcano, a large volcanic caldera formed by very large e ...

has returned and has a new island.

became a peninsula.

Islands in lakes on islands in lakes on islands in lakes

Only one lake is known to have such islands. Moose Boulder was claimed to exist in the seasonal pond of Moose Flats on Ryan Island in Siskiwit Lake on

Isle Royale Isle Royale National Park is an American national park consisting of Isle Royale – known as Minong to the native Ojibwe – along with more than 400 small adjacent islands and the surrounding waters of Lake Superior, in the state of Michigan. ...

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...

in the United States. In 2020, an expedition to the island found that it is potentially a hoax, along with the aforementioned seasonal pond.

Recursive lakes

Lakes on islands

Only a few notable examples are listed. Laguna Volcan Maderas

Lakes on islands in lakes

Lakes on islands in lakes on islands

Lakes on islands in lakes on islands in lakes

Only one such lake is known.

Notes

References

{{Reflist Coastal and oceanic landforms Coastal geography Lake islands

Lakes A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

Lists of islands Recursion