# Blue Holes auf den Bahamas (CC BY 4.0)

Blue holes are cave systems, flooded with sea water. How did the geological treasures develop thousands of years ago?

- Kind: Short
- Year: 2020
- Runtime: 1 min
- By: ZDF/Terra X/SPIEGEL TV/Christopher Gerisch/Tilman Remme/Reiner Bauer, Oliver Gurr/Oliver Roetz, Philipp Klein/Hauke Ketelsen/Richard Sako
- Archive: [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Blue_Holes_auf_den_Bahamas_(CC_BY_4.0).webm)
- Licence or status: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0) (as the archive states it)
- Credit: ZDF/Terra X/SPIEGEL TV/Christopher Gerisch/Tilman Remme/Reiner Bauer, Oliver Gurr/Oliver Roetz, Philipp Klein/Hauke Ketelsen/Richard Sako
- Who can watch: Teens profiles and older (the archive gives no rating; placed by Invisible Network from its collection and subjects)

[Watch now](https://invisiblenetwork.ai/watch/archive/commons/91074095?play=1)