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GR 20, CORSICAWhy Go? You’re a hiker comfortable with exposure who is looking for a serious physical and navigational challenge. Full Trip: This 112-mile route touches high mountain ridges and bucolic pastures as it cuts diagonally across Corsica, a French-owned island in the Mediterranean. With a reputation as the most demanding of the many long distance hikes in Europe, this grande randonnée (great trek) has become a rite of passage for many Europeans. Known for its beaches and its place in history as the birthplace of Napoleon, Corsica is also home to treacherous mountain traverses and some of the steepest summits on the continent. There is no real footpath for most of this trek and even though there are way markers, you’ll still need navigation skills to explore the varied landscape that includes dark pine and beech forests, glacial lakes, towering spires, spectacular cliffs, barren craters, verdant meadows, and alpine summits like Monte d'Oro (7,838 feet) and Monte Incudine (7,008 feet). From highpoints on the route, you can catch a glimpse of the coast and the shimmering seawater below. Broken into 16 sections with a basic refuge at the end of each section, you can sleep in a bed, eat hot meals, and socialize in the evenings. Note: Since a fatal accident in 2015, the GR 20 no longer includes the Cirque de la Solitude, a spot where the trail is so steep that hikers needed to cling on to chains in the rock to keep from tumbling down into the abyss. The chains have been removed, making this section an optional mountaineering route requiring technical equipment. The official route bypasses this section with a very demanding ascent—complete with sections of scrambling and chain-protected passages—that brings you close to the 8,878-foot summit of Monte Cinto, a peak jutting up from the sea. Distance: 112 miles When to Go: Weather is always variable, but summer is the best option. Refuges are staffed from June to September.

Photograph by Witold Skrypczak, Alamy