The Largest Delta in the Arctic

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One of the longest rivers in the world, the Lena River originates in the Baikal Mountains of south-central Russia. From there, the Lena River winds 2,800 miles (4,400 kilometers) through northeastern Siberia before emptying in the Laptev Sea.

The Lena Delta is formed by sediment from the Lena River and the roughly 500 tributaries that meet the river along the way. The Lena Delta is the largest delta in the Arctic.

The Lena River Delta stretches out 60 miles (100 kilometers) into the Laptev Sea and is 250 miles (400 kilometers) wide. More than 20 million metric tons of suspended silt and roughly 550 cubic kilometers (130 cubic miles) of freshwater are discharged into the Laptev Sea annually by the river [1].

Shaded relief map showing the location of the Lena Delta above the Arctic Circle.
Lena Delta is located above the Arctic Sea by the Laptev Sea. Map: Caitlin Dempsey. Data from Natural Earth.

Summer thaw in the Lena Delta

For seven months of the year, the Lena Delta is frozen due to its far northern location. During the short summer season, the delta thaws and becomes a wetland.

The thawing produces hundreds of ponds and lakes that dot the delta. These waters are shallow as the depth of the ground thaw is limited to about 8-16 inches (20-40 centimeters) deep. The underlying permfrost helps to keep the lakes and ponds from draining during the summer.

Satellite image of the Lena Delta during summer showing hundreds of small pools of water.
NASA terra satellite image showing the thawed Lena Delta with hundreds of pools of water. Image: NASA, July 16, 2005. [2]

The Lena Delta Reserve is Russia’s largest designated wilderness area. Many Siberian wildlife use it as a nesting place and refuge.


[1] Pratt, S. E. (2022, July 13). Lena river sedimentation. NASA Earth Observatory.

[2] Lena river delta, Russia. (2007, January 25). NASA Earth Observatory.