Crystal Gorge Conservation Area This 1.0-mile loop trail near Haverhill is generally considered easy and takes an average of 21 minutes to complete. Highlights include vernal pools and streams, making itone of the more accessible ways to observe wetlands and vernal pools as most of the trails go through swamp-like terrain without the risk of your shoes getting stuck in mud. The location is best known for its rocky ledges, andyou’ll encounter a number of iconic stone walls — remnants of the land’s past as pastureland. The area provides habitat to unique species of plants and wildlife, including the Spotted Salamander and Wood Frog which rely on vernal pools. The best times to visit are March through June, andreviewers recommend coming prepared for muddy conditions.