Beaches -- The beaches here tend to be narrow strips of sand, but protected by the North and South Forks, the waters are calm and perfect for swimming. Head to Crescent Beach and Silver Beach, both along the southwestern area of the island.
Fishing -- From May through July, the striped bass and bluefish are biting just off the island; from August through October, they migrate east toward Montauk. In either season, you can head out to the hot spots with Captain Jim Hull at Light Tackle Challenge, 91 W. Neck Rd. (tel. 631/749-1906).
Hiking -- The Mashomack Preserve, Route 114 (near the South Ferry office; tel. 631/749-1001), stretches over 2,000 acres in southeastern Shelter Island -- more than a third of the island. Ex-hunting club territory, the Nature Conservancy purchased it in 1980 and has protected its marshes, freshwater ponds, tidal creeks, and oak and beech woodlands ever since. Car-free, it's a great place to go on easy hikes and look for osprey, ibis, hummingbirds, muskrats, foxes, harbor seals, and terrapins. It's open daily April to September from 9am to 5pm; from October to March the hours are 9am to 4pm, and it's closed Tuesdays. Admission is free, with a suggested donation of $2. Park just inside the preserve entrance and pick up a trail map to hike the four well-marked trails of varying lengths and difficulty (up to 11 miles), or call the office for a guided hike.
Kayaking -- The "sheltered" waters of the island's bays make for a perfect place to slice through on a kayak, and you'll likely see deer, osprey, and other wildlife on and off the shore. Go with Shelter Island Kayak Tours, Route 114 and Duvall Road (tel. 631/749-1990). Rent a kayak ($30 per hr., 2-hr. minimum) or take a 2-hour tour ($60). The Nature Conservancy (tel. 631/749-1001) also runs a few kayaking trips around Mashomack Preserve in the summer.