Just beyond a Lake Wallenpaupack boatyard, in a neighborhood of neat summer cabins and tucked at the end of a single-lane dirt road, is a natural jewel: the 545-acre Lacawac Sanctuary. The heart of the sanctuary is pristine Lake Lacawac, formed by a mile-high glacier just 10,000 years ago, during the last Ice Age.

This lake was my ultimate destination one balmy spring morning. But I decided first to see what life was stirring on land that surrounds and protects the lake. From the sanctuary parking area, trails fan out in all directions. Since I’m a pushover for a view, I decided on a loop that included parts of three trails — and promised an overlook at Wallenpaupack.

The walking was easy, the trail well-marked, wide and mostly level. The “toc-toc-toc” of pileated and other woodpeckers echoed through the open woods. Emerald-green wetlands gleamed through islands of rhododendrons. Spring peepers and wood frogs paused their calling as I stooped to inspect masses of wood frog and salamander eggs in the still water.

Further along, a manmade pond was home to an occupied osprey nesting tower. A pair of hooded mergansers splashed and chased each other, flapping and diving in an elaborate mating display. Turtles sunned themselves near two beaver lodges.

Orange blazes led me through a deeper woodland, with more glimpses of beautiful wetlands sparkling in the sun. The trail was trending downhill. Early shoots of wildflowers such as trout lilies, columbine, elderberry and Quaker ladies – as well as rock tripe, reindeer moss and many other varieties of lichen – were everywhere. Past an old deer exclosure, a spur in the trail led to my reward: a lichen-covered rock ledge and a bench with a view of Lake Wallenpaupack, a sheer drop of 250 feet below.

Ponds, wetlands, bogs and unnamed spring runs — all the water from this preserve flows to Wallenpaupack Creek and then to the Lackawaxen River, before reaching the Delaware. The majestic Delaware River flows past Philadelphia to Delaware Bay, where it pours into the Atlantic Ocean near Cape May. The land drained by the Delaware is home to 7.3 million people, and provides drinking water for twice that many.

So conserving land such as Lacawac Sanctuary protects more than Lake Lacawac itself — it protects drinking water for millions.

The morning was fading. I finally made it to Lake Lacawac, taking a mile loop from the trailhead that started out easy and quickly became demanding. The lake is a 52-acre vestige of our very ancient past. It has been called “the southernmost unpolluted glacial lake in North America.” Its waters are so pure that today it is a center of international research on preserving and protecting lakes.

I’ve only scratched the surface of this ice-created wonder of a place, and will surely be back.

Carol Hillestad is a hike leader and writer for Get Outdoors Poconos, a grant-funded series administered by Brodhead Watershed Association.