Several forest trail options that bring you through fields of massive boulders, two streams, and a small wetlands area.
The Sourland Mountain Preserve stretches from Hunterdon County all the way into Somerset County. The trails referenced here are on the southwest side of the preserve in Hunterdon County. They are accessible from an on site parking lot at 233 Rileyville Road in Ringoes NJ.
There are several trails at this location, which add up to about 2.9 miles if you explore each section. The main service road trail brings you to several worthwhile points on the preserve. The first point would be the wetlands section. At about 0.6 miles into the service road trail you will come across a floodplain on your left side. This spot is home to Grey Treefrogs and Spotted Salamanders. This is a very unique habitat, as floodplains are not too common in central NJ.
At approximately 3/4 mile into the service road trail you will come across the Blue Trail (This section is not a loop!). I highly recommend taking this route because it immediately brings you into a field of extremely large, 200 million year old boulders. This is a great sight to see and a good opportunity to take pictures.
The White and Yellow trails at the preserve are both loop options. These are both ideal routes for running or mountain biking. The White loop totals roughly two miles, and the Yellow loop totals just over 1 mile.