We're getting a sinking feeling about these lakes ... Lakes Ohrid and Prespa are two of Europe's oldest lakes - they've been around for at least a million years! The lakes owe their longevity to tectonic activity that makes the land below them sink. The resulting valleys are called grabens, and their perpetual sinking keeps the lakes from turning into bogs. "Ancient" lakes like Ohrid and Prespa have been around through at least one ice age cycle (or 130,000 years), and geologists estimate there are only 30 such lakes left in the world. Twenty of those lakes are as old as these two. Learn more about ancient lakes, grabens and more at the link in our bio. Image Description: A satellite view of two large lakes, which appear as dark blue shapes in a green landscape. Lake Ohrid, on the left, is an elongated oval. Lake Prespa, on the right, is irregularly shaped like a backwards "C". The terrain around the lakes is forested and hilly, with dark green forested hills covering the upper right of the image, and barer tan landscapes dominating the lower left. City roads and streets are visible around the top and bottom of Lake Ohrid and the top of Lake Prespa, and rectangular agricultural fields are visible near the bottom of the image. At the top of Lake Prespa, a callout reads "Old shoreline," indicating exposed ground that was covered by water in the past.