The Copernicus Sentinel-2 mission captures Canada’s Great Bear Lake in striking colours.

Straddling the Arctic Circle, Great Bear Lake lies in the Northwest Territories of Canada. Its area of 31 328 sq km makes it the largest freshwater lake entirely within Canadian borders and the fourth largest in North America.

Irregular in shape and containing many small islands, Great Bear Lake is surrounded by boreal forests and tundra, providing a rich habitat for diverse wildlife. It’s famous for its cold, clear waters, which are covered with ice from late November through to July.

The presence of lake ice can be monitored effectively by imaging sensors and standard satellite observations. In this false-colour image, three specific bands from Copernicus Sentinel-2’s visible and infrared channels have been used to process the image. Each channel has been assigned a colour to enhance the contrasts between different surfaces. This band combination is particularly suitable for monitoring ice melt, water bodies and vegetation health.

A massive sheet of sea ice covering most of the lake can be seen in shades ranging from bright blue to cyan, depending on the ice thickness. This range of colours is due to ice and snow having a higher reflectance in the visible part of the spectrum, here assigned to blue. The image, which was captured on 17 June 2026, features an intricate network of seasonal fractures, cracks and shifting ice floes across the lake surface.

Because water reflects very little light back to the satellite, it appears dark blue or black, making areas of melted ice easy to distinguish. These dark areas are typically visible along the shorelines and in the bays, where shallower water warms more quickly than the deeper centre of the lake, creating a clear moat of ice-free water between the land and the remaining ice sheet. Black fractures of open water can also be seen in the icy surface.

Shades of green dominate the landmass surrounding the lake denoting the northern boreal forest and the tundra vegetation, greening as the Arctic summer approaches.

Distinct reddish-orange and pink patches are scattered across the green landscape, indicating exposed rocky terrain, typical of the Canadian Shield, sparsely vegetated tundra or older fire scars that have not yet fully revegetated.

The Copernicus Sentinel-2 mission is based on a two-satellite constellation. Each satellite carries a high-resolution camera that images Earth’s surface in 13 spectral bands. This capability, together with the mission’s frequent revisits over the same area and its high-resolution imagery, provides crucial information about the conditions on Earth, such as land use, vegetation health, and changes in inland water bodies and the coastal environment.