Last weekend 3 of my friends and I camped in the Jack's river falls area (not the prohibited area). Around dark:thirty a hiker walked by our campsite, which is a little unusual because the location of our campsite is the last spot on that side of the river. There are other camping areas further on but you would need to cross the river and in the 5 years we've camped in this spot we've only seen 1 set of hikers attempt this. After the guy passed our camp a few minutes passed and we noticed he hadn't crossed the river but instead was partially concealed in the trees "observing" the area. Approx 20 min passed and he returned by our site back to the main trail. The campsite we use is very remote, slightly hidden and not at all well traveled so to see someone out there in the darkness with full pack seemed odd. The guy mentioned something about watching the water level etc then moved on. At 2am that evening there was a LOUD splash/thud like the sound of a very heavy rock being thrown into the water. I instantly awoke grabbed side arm/flashlight and crawled out of my hammock. Couldn't see anyone in the river or on the bank but what kind of person goes into a camp and does that in the middle of the night? Just kinda got me all sketchy feeling and I stayed awake/half asleep for the rest of the night. You see some weird things in the woods sometimes.