Every summer, people living near the Mendenhall River in Juneau, Alaska, keep a close eye on the water level. When the river level begins to rise rapidly, it’s a sign that Suicide Basin, a small glacier-dammed lake 5 miles up the mountains, has broken through the glacier again and a glacial lake outburst flood is underway.

The most gripping week of the bear calendar has arrived. The Fat Bear Week is an annual online competition hosted by Katmai National Park and Preserve in Alaska. This event, which began in 2014 as a one-day celebration, has since grown into a phenomenon among bear enthusiasts worldwide.