When I was recently visiting Distance Hill Nature Trails, we had the opportunity to speak with the owner. We were talking about local trails in the area and he told me about a local waterfall. I have a huge love of Waterfalls, so when I can find one in the Monadnock area, I have to check it out.
Porcupine Falls is located in Gilsum and is part of the Monadnock Conservancy. The trail head is located off of Route 10 on White Brook Road. You follow the dirt road to the end, where there is a small parking lot. There is a kiosk with trail information at the trail head. It is a little under a half mile to the falls. The trail is well marked and there are some bridges and boardwalks that appear fairly new.
Since we had had rain the day before we visited, there was a nice water flow. My guess is that the falls sometimes dries up depending on the amount of rainfall we have had. The best time to visit would be in the spring or after a heavy rainfall. There is a nice pool a little bit downstream from the falls that could be a good opportunity for cooling off. It is also easy access to get under the waterfall if you want to get a nice natural shower.
Since it is a short trail I would recommend checking our other trails while in the area like Bears Den.