Mondo Knows Facts
The Great Blue Hole is a drowned cave
The circular hole in the Belize reef is a collapsed limestone cavern flooded by rising seas It measures roughly 300 metres across and about 125 metres deep, far deeper than the surrounding reef flat. Stalactites inside show it formed as a dry cave when sea level was much lower. It became famous after Jacques Cousteau dived it in 1971. It sits in Mondo's world geography collection, one of 200 facts that each trace back to the reference below.
Where this comes from
National Oceanic and Atmospheric Administration
Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.
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Son Doong Cave contains the largest known cavern passage on EarthSon Doong Cave in Vietnam features a cavern passage so massive that it could fit an entire city block.Mammoth Cave is the world longest recorded cave systemLocated in Kentucky, Mammoth Cave contains over 680 kilometres of surveyed subterranean passages.Mangroves and mudflats absorb storm energyDense roots and soft sediment slow waves before they reach the land behindSea level is not rising evenly around the worldLand sinking or rebounding changes local sea level far more than the global average in some placesNorway's coastline is longer than its land bordersMeasured around every fjord, Norway's mainland shore runs roughly 29,000 kilometresFjords are glacial valleys that the sea floodedIce cut the valleys below sea level, and when it melted the ocean moved in
🗺️ World Geographyfact 177 of 200
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Tags: coastlines, caves, belize
The Great Blue Hole is a drowned cave: the short answers
- Where does this come from, and can I check it?
- The circular hole in the Belize reef is a collapsed limestone cavern flooded by rising seas. The figure is taken from National Oceanic and Atmospheric Administration, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a world geography fact?
- Yes. It sits on the World Geography shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.