The icy Michigan morning was pitch black when photographer Amy Sacka climbed onto the back of a snowmobile at 5 a.m. She was bundled in layers of fleece and Gore-Tex, wrapped so thoroughly that only her eyes were exposed. In the frigid darkness, the snowmobile’s engine shuddered on and charged across the frozen expanse of Lake Michigan.

Her guides, Jordan Millette and Bryant Dault, were expert ice anglers. As they took off across the ice, they navigated by the dim light of a GPS screen toward a frozen Valhalla: A prime fishing spot, miles out across the frozen lake. Here they would post up for the day, drill an eight-inch-wide hole through the thick slab of ice, set their tip-ups,