Inside the question engineOpen the field notes
We draw a sea or lake and show only its outline in an equal-area projection. All three distractors belong to the same category as the correct answer, so seas are compared with seas and lakes with lakes.
The sea and lake shape quiz: how it works
This quiz tests whether you can identify a sea or lake from its outline alone, with no labels or background map. The wrong answers belong to the same category, so you compare seas with seas and lakes with lakes.
Which seas and lakes does the quiz draw?
Each round has 10 questions. The pool contains 7 seas and 18 lakes, and outlines do not repeat within a round while the pool allows it. The outlines are drawn in an equal-area projection.
Where do the outlines and areas of the water bodies come from?
Outlines come from Natural Earth data, and descriptions and areas from the source assigned to each water body: Encyclopaedia Britannica and the US Environmental Protection Agency (published 2023 and 2024).
A fact: the largest and the smallest outline
The largest outline in the pool belongs to the Caribbean Sea (2,754,000 km²), and the smallest to Vänern (5,655 km²).
Frequently asked questions
How can you recognize Lake Baikal by its outline?
A narrow, curved crescent in the heart of Siberia. It is the world's deepest lake at 1,642 m. Area: 31,722 km².
How can you recognize the Caspian Sea by its outline?
This elongated teardrop has no ocean outlet and is the world's largest enclosed body of water. Area: 371,000 km².
How can you recognize the Baltic Sea by its outline?
This branching sea with the Gulfs of Bothnia and Finland is a shallow body of water in northern Europe. Area: 377,000 km².