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The Blue Lake Rhino Cave is not named after an Rhinoceros, it was one.
The rhinoceros-shaped cave was made by highly fluid, rapid-moving basalt that was once a mature Diceratherium (an ancient ancestor of the modern rhinoceros) bull grazing on prairie when the eruption started. Its escape route was cut off by a lake, which led to the Diceratherium's fiery fate.
Death by lava sounds like a terrible way to go, but on the bright side, the Diceratherium was probably killed by the heat and poisonous gases before it was eventually covered by the lava. The remaining fluids in its corpse cooled the molten rock, which hardened it into its present shape.
In the late 1940s a crew from Berkeley made a cast of the interior of the cave. The cast is on display at the University of Washington Burke Museum in Seattle. Some bone fragments were found. The largest is the left mandible with broken teeth, indicating a mature animal comparable to a Diceratherium ancestor.
Because of its size, a crawl through the cave is not for everyone. However, if you take a flashlight with you, you may be able to see the bellybutton.
