Newton Cave is the deepest known cave in Washington State. The lowest point reaches a depth of 800 feet below the entrance
Overall, Washington is not the best state for cave systems. The best caving to be found in western Washington is located inside Cave Ridge located between Snoqualmie Mountain and Guye Peak. Much of the cave systems on cave ridge have yet to be fully explored.
Unlike your typical limestone caves, the caves of Cave Ridge were formed by the erosion of a large vein of white marble. There are several entrances to different systems including the formidable Hellhole Cave, Danger Cave and others.
For liability reasons, the exact location of Newton Cave will not be posted. Many of the caves begin with an immediate drop. So it is not suggested that you enter any cave unless you are certain of which cave it is and you are also ready to rappel.
The combination of deep shafts and slippery down-sloping slabs makes spelunking on Cave Ridge EXTREMELY HAZARDOUS. Only experienced cavers and rock climbers should explore these systems. Any major injury can ultimately lead to death because a timely rescue is impossible.
Anyone planning an expedition should have rope, ascenders, helmets, and belay devices. All members of the expedition should carry 3 sources of light with back-up batteries.
Remember that Newton cave is a live cave, so flowing water can present a problem. It is suggested that you go in August or September after a dry spell to avoid getting totally soaked. Bring extra synthetic layers for the cold damp environment.
There is only one book which describes where to find Newton and the other caves of Cave ridge. Caves of Washington by William R Halliday was published in 1963. There are very few copies of this book. If you find one, it will be expensive.
Below are some recollections from Stephen Sickles who made some of the early explorations to the bottom of the cave in 1967. He has asked me to share a few of his photos.
I have been in Newton Cave several times, and went all the way to the bottom (80' rappel) on final drop. This was done in 1967. At that time, I was 18 years old and into rock climbing. In those days, it was goldline rope and carbide lamps.
Everytime we went caving up there, it was always overnight trips on the weekend. We typically camped under tarps to save weight....as we always had heavy packs with caving gear....that includes a rope, rope ladder and some hardware....in those days it was pitons. We would alternate between hiking up from Alpental side and the Commonwealth Basin approach.....I didn't seem to have a preference for which way to hike....so we just alternated between the two approaches. Each of us would carry also a gallon of water, as Cave Ridge was bone dry for camping. Often, it would be around midnight before we got out of the cave...
In Newton Cave, there was once this sharp blade of a rock that hung off the ceiling on one of the passage ways. You had to crawl underneath it to get by....and we always thought if it fell on you, you would be cut in half. Finally it did come down....but not on anyone.....then, it was a bit more relaxing to do that stretch. We called that rock flake the "Gillotene"
One of my caving friends at that time was living in Seattle and he knew some of the cavers from a caving club. We took one of those members with us.....but it was kind of a joke....the poor guy was overweight, out of shape....didn't like being squeezed in the narrow spots...and on the hard rock climbing parts of it....he was frightened all the time.