Which lake holds more water?
Inside the question engineOpen the field notes
Both lakes use the same scale and an equal-area projection, so their visible surfaces retain the true proportion. The question, however, is about volume, which also depends on depth. The volume difference becomes smaller at each stage.
About the quiz: Which lake holds more water?
This quiz tests whether you can tell a lake's surface area from the amount of water it holds. You see both lakes at the same scale, but volume also depends on depth, which a map cannot show.
How are the questions built?
Each round has 10 questions. Pairs are drawn from 18 lakes with a verified volume, and no pair repeats within a round. The volume gap between the answers shrinks at each stage: from 50% to 150% in the first questions to only 2% to 8% in the last ones.
Where does the data come from?
Areas and volumes come from the source assigned to each lake: Encyclopaedia Britannica and the US Environmental Protection Agency (published 2023 and 2024). Outlines come from Natural Earth data.
A fact from the data
The largest surface in the pool belongs to Lake Superior (82,100 km²), but Lake Baikal holds the most water: 23,615 km³ compared with 12,100 km³.