ナショナルジオグラフィックさんのインスタグラム写真 - (ナショナルジオグラフィックInstagram)「Photo by Robbie Shone @shonephoto | With iconic Matterhorn mountain looming large in the background, two explorers search the surface of ice for moulins and caves that could lead them down to the contact point where the glacier meets the rock of the valley floor. During the middle of the night, when it is the coldest and there is no running meltwater, is the safest time to explore these caves.」3月22日 4時06分