“My friends can’t believe I go camping in winter. They think it’s crazy.” But 13-year-old Emika loves it. It’s just as beautiful as in summertime. “You just need a good tent and sleeping bag, and warm clothes.” Every school vacation she and her cousin Antti, who is kind of like a big brother to Emika, go to the vast Saimaa Lake, an amazing nature reserve in Finland with thousan...