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3. What is an anchialine pool?

**What is an anchialine pool?**  An anchialine pool is an enclosed water body or pond with an underground connection to the ocean. Bermuda Triangle map*Anchialine pools form some of the longest submerged caves structures on Earth.  (Image courtesy of National Science Foundation)* The word “anchialine” (AN-key-ah-lin) comes from  a Greek word meaning “near the sea." These  typically small pools, which form in limestone or volcanic rock, are located  throughout the world but are most common in the Hawaiian Islands and on Mexico’s  Yucatán Peninsula. Anchialine  pools have their own unique ecosystems populated by tiny and often rare species  of crustaceans, fish, and eels. Among  these species is Hawaii’s legendary red shrimp, the *ʻ**ōpaeʻula*(oo-PAY-oo-la). Water levels in the pools can fluctuate in  response to ocean tides. Due to their subterranean connection to the ocean,  anchialine surface waters are often brackish and become more saline (salty) with  increasing depth. Many  anchialine pools are found in underground cave systems and are favorite  destinations for cave divers seeking to observe unusual cave species. One such creature  is the Mexican blind tetra, an albino fish that has lost not only its sight but  also its eyes! More  than half of the world’s known anchialine pools are found in the Hawaiian  Islands. On  the Big Island of Hawaii, the NOAA Restoration Centerfunded a two-acre  restoration project for the pools, which have fallen victim in recent years to  invasive fish species that upset the pools’ natural balance. To restore the ponds, nearly 400 citizen volunteers helped  remove the foreign invaders and reintroduce native vegetation. The restored sites  are monitored twice a month to remove algae and maintain the revitalized  vegetation. Scientists  are learning that the pools’ fragile natural balance makes them good indicators  of overall coastal ecosystem health.
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  **Last updated:** 10/04/23 **Author:** NOAA How to cite this article Contact Us


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