GETTING THERE: New London, Conn., is the starting (and end) point of the loop. To go completely car-free, fly from Washington to New York (round-trip fares from $115) or Hartford., Conn. (from $78 round trip on Southwest), then take Amtrak to New London (from $90 and $56 round trip, respectively). The ferry terminal is a short walk from train station.
By car, New London is about 360 miles, or a six-hour drive, from D.C. There's limited parking at the terminal for $10 a day, and a lot across the street (860-443-1775, $6-$15 daily).
FERRYING AROUND: The full circuit involves five ferries. All but two go year-round; the others roughly run from Memorial Day to Columbus Day.
* The Cross Sound Ferry, which travels from New London to Orient Point, N.Y., takes about an hour and a half and costs $10.50 one way, plus $2 for a bike. Info: 860-443-5281, www.longislandferry.com.
* Shelter Island's North Ferry Co. (631-749-0139, www.northferry.com) runs a small commuter boat that takes less than five minutes to sail from Greenport, N.Y., to the north end of the island; one-way fare for a passenger and a bike is $3.
* On the opposite end of the island, the South Ferry Co. (631-749-1200, www.southferry.com) goes to North Haven, N.Y., for $3 one way for a rider and a bike; travel time is minutes.
* The Viking Fleet (631-668-5700, www.vikingfleet.com) runs the Montauk-Block Island route only once a day, at 9 a.m. The trip takes 1 hour 45 minutes and costs $25 one way, plus $7 for a bike. Service ends Oct. 10.
* The Block Island Express's high-speed ferry, which sails to/from Block Island and New London until Columbus Day, takes just over an hour and costs $16, plus $10 for a bike. Info: 860-444-4624, www.goblockisland.com/home.htm.
BIKING: The paved bike lane around Long Island's North and South forks is basically flat and becomes congested only around the towns. Parts of Montauk and Block Island are hilly, but nothing a lower gear can't handle. Depending on how you plot the trip, maximum daily distance is about 20 miles, though you can add more with side trips -- or less, by upping your idle time.
If you don't want to lug your bike from Washington, New London's Terra Cyclery (154 Williams St., 860-443-7223, www.terracyclery.com) will sell a used bike for $150, then buy it back for $100 up to a week later. Mystic Cycle Center (42 Williams Ave., 860-572-7433), about a half-hour away in Mystic, Conn., rents comfort mountain bikes for $20 a day or $40 for four days.
STAYING THERE: We overnighted in Shelter Island and Montauk (strongly advised, since you have to catch a morning ferry to Block Island). For accommodations in other towns along the Long Island portion, such as East Hampton and Sag Harbor, contact the Long Island Convention and Visitors Bureau (see Info below) or visit the Sag Harbor Chamber of Commerce's Web site, www.sagharborchamber.com.
Shelter Island's most elegant property is the Ram's Head Inn, a secluded 17-room Colonial tucked away on Ram's Island (no ferry, just a causeway). However, its in-town sister isn't so bad, either. The Chequit, up the hill from the north end ferry, is a Victorian inn decorated in summer brights. In-season rates for the Ram's Head start at $105 weekdays with shared bath; for the Chequit, $80 weekdays for the summer cottage (there are three buildings). Two-night minimum for weekends. Info: 631-749-0811 (Ram's Head), 631-749-0018 (Chequit), www.shelterislandinns.com.
In Montauk, a number of old-school beach motels with names like Beachcomber and the Breakers sit along Old Montauk Highway, just across the street from the ocean. The Shepherds Neck Inn (631-668-2105) is not on the beach but its related property, the Shepherds Beach Motel (631-668-6700), is. The inn's rooms are modest, but the lush gardens and pool make up for its lack of style. Inn rates from $79; motel rooms from $140 per night. Info: www.shepherdsneckinn.com.
To be in the center of Block Island's action, stay on or around Water Street, near Old Harbor (where the ferry to New London departs). The National Hotel (800-225-2449, www.blockislandhotels.com) is a 45-room landmark property with a wrap-around porch/bar where you can be in the scene without ever vacating your seat. Doubles from $149. For the best ocean views -- and best croquet lawn -- the hilltop Spring House (Spring Street, 800-234- 9263, www.springhousehotel.com) has hosted such notables as Mark Twain and Billy Joel; rooms from $250 in high season.
WHERE TO EAT: The Ram's Head Inn's restaurant on Shelter Island offers upper-crust dining without the airs. Dinner choices include pignoli-crusted flounder ($24), roasted saddle of rabbit ($23) and rainbow parpadelle ($18). Planet Bliss (24 N. Ferry Rd./Route 114, 631-749-0053) serves organic world cuisine, such as coconut Thai stew ($22), Caribbean jerk chicken ($21) and lobster ravioli ($20). In Amagansett, stop for a dosa (sour-dough crepe made of rice) or uttapa (a pancake-flat dosa) at the Hampton Chutney Co. (Main Street, Amagansett Square, 631-267-3131; $7-$12).
Near the Montauk ferry, Gosman's (Flamingo and West Lake Drive, 631-668-2549, www.gosmans.com) takes up the dock with dining options: Choose from the seafood market, takeout window/clam bar, cafe or more formal dining area -- all with water views. East by Northeast (51 Edgemere St., 631-668-2872) spices up its platters with a pinch of Asia; the plates of fish, chicken, tofu and vegetables, etc., are enormous and cost $24 to $36 -- but feed two.
For fish and chips, chowder, burgers and cold beer on Block Island, try Beachead on Corn Neck Road (401-466-2249; meals $6-$13), across from the beach. The romantic Hotel Manisses (Spring Street, 800-626-4773) caters to all budgets and tastes: Its restaurant prepares fine cuisine, such as lobster thermidor and filet mignon (entrees from $22); the Gatsby Room serves lighter fare (from $9); and the Upstairs Parlor sweetens the evening with desserts and flaming coffees. End the night with a pint and a (Celtic) song at Mahagony Shoals bar on Payne's Dock.
WHAT TO DO: Dozens of wineries populate the North Fork, starting with Ternhaven Cellars (331 Front St., Greenport, 631-477-8737, www.ternhaven.com), where you can tour for free the auto garage-cum-winery and sample three red wines for $2. Bike along routes 48 or 25 for more vineyards. Info: Long Island Wine Country, 631-369-5887, www.liwines.com. The Mashomack Preserve (631-749-1001, www.nature.org; $2 suggested donation) on Shelter Island offers almost 2,100 acres of Nature Conservancy-protected land great for hiking and wildlife spotting. Bone up on Sag Harbor's whaling history at the Whaling and Historical Museum (200 Main St., 631-725-0770, www.sagharborwhalingmuseum.org; $5), which is featuring a surfing exhibit until Nov. 1.
About four miles north of East Hampton, you can step on Jackson Pollock's paint-splattered floor and tour his and wife/painter Lee Krasner's house at the Pollock-Krasner House and Studio Center (830 Springs-Fireplace Rd., 631-324-4929, www.pkhouse.org; $5 self-guided or $10 reserved guided tour); open Thursday to Saturday only. Before leaving, ask for a map to the Green River Cemetery, where the abstract expressionist and Krasner are buried. Also check out the graves of other buried artists, whose tombstones are works of art. East Hampton also has a few windmills to view curbside.
The Montauk Point Lighthouse (888-MTK- POINT, www.montauklighthouse.com; $6), which looms at the end of the South Fork, offers tours and uninterrupted views. Sportfishing is big in Montauk, whose waters are filled with tuna, striper, bluefish and, yes, sharks. Book a charter at the Montauk Marine Basin on West Lake Drive, or stay on land and see the full-scale model of the largest great white (17 feet) landed by rod and reel.
Block Island has 17 miles of beaches, and each has its own personality: Scotch Beach is sporty and social; Mansion Beach, family-friendly; and Black Rock, surfer cool. For intense biking and/or hiking, get lost in the flora-dense Rodman's Hollow, which starts on Cooneymus Road and leads to the bluffs.
INFO: For Shelter Island, the unofficial Web site www.shelter-island.org has the island lowdown and links to the chamber of commerce. Block Island Chamber of Commerce, 800-383-BIRI, www.blockislandinfo.com; Montauk Chamber of Commerce, 631- 668-2428, www.montaukchamber.com. For the North and South forks: Long Island Convention and Visitors Bureau, 877-FUN-ON-LI, www.licvb.com.
-- Andrea Sachs