These glacier caves were visited and documented at least as early as 1908.
[1] They have a varied natural history, as their size and even existence has changed over time, from a maximum surveyed length of 13.25 kilometers in 1978, to not existing at all during both the 1940s and 1990s[2] due to glacial recession.
In 1978 they were the longest mapped system of glacier caves in the world.
This Pierce County, Washington state location article is a stub.
You can help Wikipedia by expanding it.This article about a cave in the United States is a stub.