Quinnipiac River State Park
The bottom four miles of the Blue Blazed Trail from North Haven to Cheshire.
Four miles up, four miles back.
Destination Distance From Downtown
If you want a trail to walk on, bring a machete and some hip waders. The blazes are marked through a flood plain, so the trail changes with the river; don't expect a bridge for each river crossing. Also, the plants grow faster than they get cut back.
Time To Complete
I gave up and turned back after 45 minutes, but I've read an account by an experienced hiker who walked the eight mile round-trip in 3.5 hours.
The park is open year-round but the ground gets so muddy and the vegetation grows so thick in summer it's all but impassable. Wait until the winter die-back.