The aquatic moss of Crater Lake

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The aquatic moss of Crater Lake. Excerpted from the Visitors Center film "Crater Lake Into the Deep".

Aquatic moss
Aquatic moss, living in Crater Lake at depths between 25 and 150 yards, grows on a deep lake mooring line.


  • New information on moss distribution, biomass, and history in the lake is one of the most significant development in the ecology of Crater Lake in 40 years.
  • the moss is a type of bryophyte (Drepanocladus sp. and Fontinalis sp.)
  • the moss is most common around Wizard Island, but can be found around the margins of the entire lake
  • the moss grows at 25-140 meters
  • field studies used remotely-operated vehicles (ROV), multi-beam sonar, side-scan sonar, and sonar back-scatter analyses to map the moss locations
  • dead moss layers, underlying the live moss, have been dated at several thousand years old
Description of the moss deposits in Crater Lake
This graph shows a cross-section of the bottom on the east side of Wizard Island, with the aquatic moss deposits shown by the arrows "Thick Peat Sediments" and "Fumaroles".  The thick peat sediments are remnants of dead moss that have accumulated over hundreds or thousands of years.  Live moss (not shown) still live on the surfaces of some of the peat deposits. The fumaroles are curious pits, depressions, and tubes in some areas of the peat deposits.


Tunnel in dead aquatic moss in Crater Lake
A tunnel through dead aquatic moss at the bottom of Crater Lake.  The dead moss layers accumulate over thousands of years, sometimes reaching 40 yards thick.  Various pits, holes, and depressions form in the dead moss which vary in size from inches to tens of yards in diameter.



  • there is a strange collection of tubes, pits, holes, and depressions on the surface of the dead moss layers
  • some of the holes begin at the surface of the moss layer and stretch up to five meters into the bottom
  • the strange formations are several inches to tens of meters in diameter
  • the process that forms the tubes and holes is unknown

Last updated: October 27, 2021

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