Small waves lap against the sandy shoreline of Wisconsin's Rock Island State Park.

Rock Island State Park in Door County

Getting to Rock Island State Park, the most isolated state park in Wisconsin’s system, necessitates two ferry rides. When you get here, it’s a magnificent retreat: a small island, yes, but with delicious solitude, icy but gorgeous beaches, and the loveliest starry skies and sunrises in Wisconsin.

Atop the seventy-five foot high viewing platform overlooking the water.

Peninsula State Park in Door County

Deeded to the state in 1909, Peninsula is the second-oldest park in the state system and the most visited—it draws more visitors per year than Yellowstone National Park.