Katmai

If you've ever seen the photo of a brown bear catching a leaping salmon in midair, there's a strong chance it was taken at Brooks Falls, inside Katmai National Park. The park protects some of the highest concentrations of brown bears anywhere on Earth, drawn to the Brooks River each summer by a salmon run that peaks twice: once in early-to-mid July as fish arrive, and again from late August into fall as spawned-out salmon become easy pickings for bears fattening up before hibernation.

Reaching Brooks Camp requires a floatplane, since the only way in is a roughly 20-minute flight from King Salmon that lands directly on Naknek Lake. Every visitor completes a mandatory bear-safety orientation, sometimes called bear school, before setting foot on the trail to the viewing platforms, a genuinely necessary precaution in a place where bears regularly walk the same paths as people. Beyond the bears, the Valley of Ten Thousand Smokes, a roughly 700-foot layer of volcanic ash from a massive 1912 eruption, offers an otherworldly landscape unlike anything else in the park system.

Come for the bears at the falls. Stay long enough to see the valley that a single eruption buried in ash more than a century ago. Read the story, book your floatplane and any camping or lodge reservation well ahead, and when you leave, collect the stamp.