There is something slightly unusual about an island sitting inside a lake. Unlike ocean islands, these pieces of land are enclosed by freshwater, often hidden within vast inland landscapes that many people never associate with islands at all. Some are remote wildernesses, others support towns, roads and centuries-old communities. A few are so large that they contain forests, mountain ranges and lakes of their own.Their origins are just as varied. Some were shaped by volcanic eruptions, some emerged from ancient geological upheavals, and one owes its existence to a meteor impact that happened long before dinosaurs disappeared. Measured by surface area, these are the largest lake islands on Earth, each occupying a unique place within some of the world’s most remarkable freshwater environments.According to WorldAtlas, check the list of the 10 largest lake islands in the world.
World’s 10 largest lake islands, ranked by size
1. Manitoulin Island
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Covering 2,766 square kilometres, Manitoulin Island in Ontario, Canada, remains the largest island located within a freshwater lake anywhere in the world. It lies in Lake Huron and is large enough to support numerous settlements, extensive forests and a network of rivers flowing across its landscape.Part of what makes Manitoulin distinctive is the number of lakes found within the island itself. More than a hundred are scattered across its interior. Lake Manitou is the largest among them and holds another record as the biggest lake situated on a freshwater island. The geographical layering goes even further, with Treasure Island sitting inside Lake Mindemoya, creating one of the planet’s best-known examples of an island in a lake on an island in a lake.2. René-Levasseur Island
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René-Levasseur Island in Quebec occupies about 2,020 square kilometres and sits at the centre of the circular Manicouagan Reservoir. Seen from above, the surrounding water forms a striking ring, giving the landscape an appearance unlike almost anywhere else on Earth.The island’s story began roughly 214 million years ago when a large meteorite struck the region, creating a vast crater. The central uplift produced by that impact survived while surrounding areas gradually eroded. Modern reservoir construction later flooded the area, leaving the elevated centre isolated as an island. Mount Babel, rising to 952 metres, forms the island’s highest point.3. Sääminginsalo
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Eastern Finland’s Sääminginsalo covers approximately 1,069 square kilometres. Unlike most entries on this list, it became an island through human intervention rather than natural processes.The turning point came during the eighteenth century when the Raikuu Canal was cut through a narrow land connection, separating the area from the mainland. Today it sits within the intricate waterways of the Lake Saimaa system. The island is also known for the enormous wooden church at Kerimäki, recognised as the largest wooden church in the world, while nearby Savonlinna and its medieval castle add to the area’s historic character.4. Olkhon Island
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Olkhon Island lies within Russia’s Lake Baikal, the world’s deepest freshwater lake. Covering around 730 square kilometres, it stretches for more than 70 kilometres across the lake and contains an unexpectedly varied landscape.Forests, grasslands, rocky hills and sparsely vegetated areas all exist within a relatively confined area. The island holds cultural significance for the Indigenous Buryat people and remains associated with long-standing spiritual traditions linked to the region. Mount Zhima reaches 1,276 metres, while the village of Khuzhir serves as the island’s principal settlement.5. Samosir Island
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Samosir Island occupies roughly 630 square kilometres within Indonesia’s Lake Toba. Both the island and the lake owe their existence to a colossal volcanic eruption that occurred around 75,000 years ago.Lake Toba fills an enormous caldera left behind by that eruption, while Samosir emerged within the basin itself. The island is often cited for its unusual geographical position because it sits within a lake that is itself located on the island of Sumatra. It remains closely connected to the culture of the Batak people and attracts visitors interested in the lake’s volcanic landscape.6. Isle Royale
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Situated in Lake Superior, Isle Royale covers about 535 square kilometres and forms the core of Isle Royale National Park in the United States. Although politically part of Michigan, the island feels distinctly isolated due to its location far from major population centres.Its forests, ridges and lakes provide habitat for moose, wolves and numerous smaller species. The island has become particularly important for ecological research because scientists have monitored predator-prey relationships between wolves and moose there for decades. Access is limited to boats and seaplanes, helping preserve its remote character.7. Ukerewe
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Ukerewe, located in Lake Victoria, spans roughly 530 square kilometres and ranks as Africa’s largest inland lake island.The island sits north of Tanzania’s city of Mwanza and is surrounded by numerous smaller islands. Fishing and agriculture remain central to local livelihoods, while the town of Nansio serves as the island’s main administrative and commercial centre. Its deeply indented coastline creates a landscape marked by bays and inlets extending into the surrounding waters.8. St. Joseph Island
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Another large island in Lake Huron, St. Joseph Island covers around 365 square kilometres near the border between Canada and the United States.The island’s interior contains dozens of small lakes and rises towards a central high point locally known as “the Mountain”. Forests dominated by hardwood species cover much of the landscape. Along its southwestern edge, wetlands and shoreline habitats support migratory birds, leading to the establishment of a protected bird sanctuary during the mid-twentieth century.9. Drummond Island
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Drummond Island occupies about 347 square kilometres within northern Lake Huron and is one of the largest islands associated with the Great Lakes system.The international boundary between Canada and the United States passes through nearby waters, although most of the island belongs to Michigan. A defining feature of Drummond Island is its extensive alvar habitat, where thin soils cover limestone bedrock and support specialised plant communities. Such environments are relatively uncommon globally, making the island ecologically significant.10. Idjwi
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Idjwi lies in Lake Kivu between the Democratic Republic of the Congo and Rwanda. Covering approximately 285 square kilometres, it completes the list as the tenth-largest lake island in the world.The island stretches for about 70 kilometres along its length and supports a substantial population. Despite being located within a region that has experienced periods of instability, Idjwi has largely maintained its own distinct rhythm of life. Agriculture forms the basis of the local economy, and communities are spread across the island’s narrow landscape overlooking Lake Kivu.
