I SPENT A SUMMER GUIDING sea-kayaking trips in Wisconsin's Apostle Islands National Lakeshore, pinballing between the islands' sea caves, lighthouses, and hidden campsites. But the objective was the same: Get to Outer Island. Although it's only a four-mile open-water crossing from Stockton Island, it's not to be taken lightly: Lake Superior isn't an ocean, but no one told her that. She can get all swelly on you in a second. Which is part of the reason the shaded campsite along the island's sandy southern tip feels especially serene. If a storm rolls in, you might be stuck there for a day or two. Bring extra food. And a book.