Search for Pumpelly Cave: Mount Monadnock

We’re standing in a large clearing along the Dublin Ridge. We are two and a quarter miles from either end of the trail. One end being the summit, the other being the starting point next to Dublin Lake. It’s the longest of the five main trails on Mount Monadnock at 4.5 miles in length or 9 miles round trip. This is the Pumpelly Trail.
Mount Monadnock has an interesting history, well, interesting as far as mountains go. Both geologically and socially, Monadnock is a unique magical place for many New Englanders. From the likes of Henry David Thoreau, Ralph Waldo Emerson, Ulysses S. Grant and thousands of visitors every year, Mt. Monadnock has been known as the most hiked, most written about, most painted and most loved mountain in America.
Among many interesting historical facts about the mountain, some of the more interesting things are what is kept secret. There are many hidden places on the mountain which are not publicized by the State Park and for good reason. Unfortunately, these secret places are subject to vandalism if left to the devices of the general public. On the other hand, it makes it all the more difficult for us curious adventurers to find. Though I suppose it wouldn’t be much of an adventure if it was easy…
One such hidden location is Pumpelly Cave. Though it’s common name is named after the trail which it is located near, the official name given by it’s builders is Megalithia. Built by the sons of famed geologist/explorer Raphael Pumpelly and renowned naturalist painter Abbott Thayer, the cave was constructed as early as 1902 and remained a secret for many decades. To this day only a select few know of it’s location on the mountain.
We’re hunched over a book, trying to keep the wind from wildly flipping the pages, examining an old photograph of Pumpelly Cave from the 1950s. I had bought the book, Monadnock: More than a Mountain by Craig Brandon, a week earlier in the hopes that it would either give the location or at least hint at the location of the cave. Aside from pictures of the cave and the story of it’s history there was little information to help find it’s whereabouts.
Fortunately, my brother Donald had the great idea to match the background of the picture with a location on the trail. You see, the background image of the picture shows a certain angle of the second crag along the Dublin Ridge before reaching the summit of Mount Monadnock. This particular view, from what we could tell, could only match the current view along certain parts of the Pumpelly trail.
In addition to the background image of the old picture, we estimated that the cave was located approximately 2 miles from the road. After reading the story of the cave’s builders, Raphael Pumpelly II and Gerald Thayer, the book says that the two would haul their building supplies two miles up the mountain from the nearest road, putting in over a thousand hours of work on their own secret hideaway.
We are walking around the large clearing where we think the cave is located. We notice that on one side there are many large rock cliffs, a perfect spot for building a hidden shelter. We veer off the trail into the woods, walking around large cliff faces and closely examining the surrounding terrain. Of course the task is quite challenging, especially since the shelter was designed to blend into the natural landscape. It’s for this reason that most people call it a cave when in reality it’s a man made shelter.
After walking along the side of the ridge for a quarter mile through dense pine forest and scrambling over large boulders we finally give up and head back to the main trail. The sun is getting lower in the sky and the reality of finding Pumpelly Cave is not in our cards. This particular part of Monadnock lore will remain a secret… for now.

Great job…I really liked it! Can’t wait to see your next adventure….
Nice job! When is the next expedition?
very good. wish i was younger to go exploring too. will be looking for the next time. Grandma
Thanks for the comments. You can check back every Wednesday for a new adventure.
did you ever find the cave? I can’t even find a picture on the net. My son and I are going back to look again in a couple weeks.
Have you ever seen wreckage from the plane crashes on the mountain?
@Dave,
We still haven’t found it yet, though will likely try again in late Fall, early Winter, as I believe it will be much easier to spot without all the leaves on the trees and bushes. There’s an old picture and some history on it from the 1950s and is published in the book: Monadnock: More than a Mountain and there is another picture on this site, which also claims that the cave is near Town Line Peak, wherever that is.
I have never seen any plane crash wreckage but after reading the book, I seem to recall that it said it was pretty much all removed from the mountain.
Good luck on your search, let me know if you find it!
I would really like to go looking for the Pumpelly Cave. Since I am a bonified Pumpelly and a distant relative of the Raphael Pumpelly family it makes it more intising. I have never made it that far north. This is part of my heritage that I would like to persue. I am an avid outdoorsmans and love family history stuff. I have been to some of Raphael’s family homes in upstate New York. I will pay attention to this site to se if you ever find the cave.
I’ll give everyone a great hint… It is almost unthinkable to access Pumpelly Cave from the Pumpelly trail…
Try a different Trail
I have climbed mt monadnock many times as a teen and found the cave first time without even knowing it existed. It is very weel hidden along the edge of the bluffs. You can stand 10 feet away and not see the entrance!! Pines are right up against the entrance and there is a very heavy wooden door with a large chain on it to seal the entrance. Inside was a small potbelly stove and two beds as a bunk. The log book is full of hikers that stayed there and my name is in there also now. Several garden tools where there and soom food in jars. Not much else is there but it was still cool. I found it when I was 14 and now I am 51 and I plan to go back after all these years and see if I can find it again. There is also a cabin up there!!
Near the bluffs huh? I find myself at or around Mt Monadnock very much. I’ll have to go searching for it.