Stockholm looks sharp from the Strandvägen waterfront. But the real payoff starts where the city ends: an archipelago of roughly 30,000 islands, pines that took root around the time the Mayflower sailed, and a Viking-era main street still running on its original line. This guide to the best day trips from Stockholm is built for the traveler who plans his own route, whether that's behind the wheel of a Volvo, a Range Rover or a 911, or clipped into a carbon frame.