冬季奥兰卡国家公园Myllykoski风景区中的漩涡，芬兰库萨莫 The whirlpool in Myllykoski scenic area at winter in Oulanka National Park, Kuusamo, Finland (© Lassi Rautiainen/Minden Pictures)

冬季奥兰卡国家公园Myllykoski风景区中的漩涡，芬兰库萨莫 The whirlpool in Myllykoski scenic area at winter in Oulanka National Park, Kuusamo, Finland (© Lassi Rautiainen/Minden Pictures)

Winter in the Finnish wilds

Don't be fooled by this frozen scene's tranquility. Once the snow melts in northern Finland's Oulanka National Park, the river's gentle swirl will turn to deafening rapids, hosting rafters as well as waterfall-peeping tourists. But there's time to enjoy the winter calm, since the region's wintery cold regularly stretches into April or May.

The partly frozen whirlpool churns near Myllykoski, a defunct mill that's now a resting point along Finland's busiest nature trail, Karhunkierros. The 50-mile route begins more than 500 miles north of Helsinki, with midsummer hikers enjoying treks lit by the midnight sun. For determined skiers and snowshoers, portions of the trail remain open through the frigid winter. Not feeling quite that intrepid? Chill at home with today's ice-themed quiz.