Letea Forest, Danube Delta, Romania

If Earth ran on routine check-ups, wetlands like the Danube Delta, shared between Romania and Ukraine, would top the list.

This vast landscape quietly filters water, absorbs floodwaters and shelters wildlife on a remarkable scale.

Covering more than 5,800 square kilometres, the Danube Delta Biosphere Reserve is one of Europe's largest and best-preserved wetlands.

It's where the Danube River finally slows down, splitting into channels, lakes, reed beds and marshes before meeting the Black Sea.

Letea Forest, featured in today's image, is a part of this vast biosphere.