Hubbard Glacier can be defined: x kilometers long by x meters wide. We can put it on a map—part of the Russell Fjord Wilderness, which is bounded by the Wrangell-St. Elias National Park and Preserve, the continent’s largest protected area, sprawling across Alaska and southern Yukon Territory. But sometimes the best thing to see is nothing at all. Glaciers create their own weather, and they like fog; at times, it can feel like the ship’s sailing through clouds, and glimpses of green and blue are the only colors. Deep fog sounds different than clear air, too. Listen hard.