This FKT follows the New England Trail from Underwood Street to and around Whiting Reservoir and back. To keep it consistent park at the bike path at the corner of North and East street and run to the Underwood entrance of the New England Trail (about 1/3 of a mile). This is a good warmup as the first mile of the New England trail will be all uphill. Follow the White Blazes all the way to the reservoir. The Reservoir has an easy path to follow around and then follow the white blazes back to Underwood Road and the bike path parking.
This particular section of the New England trail has challenging elevation and breathtaking views as your run along the cliffs overlooking Easthampton, MA. Along the way you'll hit Dry Knob, Goats Peak and Mount Tom which is a favorite of many local runners and deserved an FKT with this being the most obvious option and easiest to follow. On the way back you'll be immediately greeted by the steepest and most exhausting climb from the Reservoir back up to Mount Tom before heading back.
