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