Once away, it is never enough for an expatriate Shoreman to visit his homeland now and again, bringing back spouse and children at Christmastime or during a summer break so that they might see and be seen, only to leave again as soon as duty has been done and neither side can stand a minute more of the other. No. What Eastern Shoremen seek is a permanent end to their diaspora, an unconditional return to their flat loam, pine forests and broad salt marshes.

The next plane or bus may stir hope and optimism in a city kid from Chicago or a Mississippi farmboy. The Eastern Shoreman is not immune to such emotions. The novelist John Barth, a native Shoreman, once wrote to the effect that the unrelenting flatness of Delmarva powers its sons and daughters to strive upward and outward. True. But they always think in terms of a round-trip ticket. To the Eastern Shore

T here are three ways to reach Delmarva from New York by car: to the south end of the Delaware Memorial Bridge by the New Jersey Turnpike and thence down U.S. 13; from Washington-Baltimore to U.S. 50 and east across the Chesapeake Bay Bridge at Annapolis or, from the south, by the Chesapeake Bay Bridge-Tunnel. The $9 toll provides an over-and-underwater highway crossing of the Hampton Roads that, on a hazy day, is an automobile sea cruise. Out of sight of land, one is apt to cross the bow of an aircraft carrier or a nuclear submarine.

On a drive from New York to destinations in the south, the detour down the peninsula to Cape Charles and then by bridge-tunnel to Norfolk is well worth the time. You can rejoin I-95 at Emporia, Va., about 90 minutes west of Norfolk.

Delmarva's Atlantic coast is charming, but it is not the essence of the Eastern Shore. The prodigious protein factory of Chesapeake Bay is what brought the first English settlers and the bay side of the peninsula - the western shore of the Eastern Shore, if you will, where some claim the natives are born with webbed feet - expresses the watery ethos best.

Accordingly, the motorist southbound on U.S. 13 should bear right onto U.S. 301 at the well-marked opportunity and cross into Kent County, Md. There, the scenic route is recommended - down Md. 213 through Chestertown and Centreville, recrossing Route 301 and connecting with U.S. 50-South near Wye Mills. Fifteen miles ahead on Route 50 and barely five hours out of New York some of the choicest rewards on the Eastern Shore lie along the Tred Avon and the Miles Rivers. Dockside Dining The well-marked right off U.S. 50 towards Saint Michaels leads to antiques (at Royal Oak) and the boutiques, restaurants and Chesapeake Bay Maritime Museum at Saint Michaels, where boats and cars park side by side. Noteworthy restaurants there are The Inn (301-745-5178) at Perry Cabin, a restored 1800's mansion with a stunning view of the Miles River, The Crab Claw (301-745-2900), which is part of a marina, with boats abounding, and Longfellow's (301-745-2624). A la carte main courses at The Inn run from $1.95 to $7.95 at lunch, $7.95 to $18.95 at dinner; a simple lunch at The Crab Claw is about $4, a typical dinner about $15 a person with drinks; lunch at Longfellow's ranges from $3.50 to $8.95, complete dinners, without drinks, from $8.95 to $10.95. Accomodations Best of all for the weary traveler, if he has had the foresight to make reservations, there wait, by the frequent 15-minute ferry rides across the Tred Avon from Bellevue to Oxford, the Robert Morris Inn at Oxford (ancient and engagingly creaky with haute cuisine) or the Tidewater Inn in Easton, with the best food, drink and overnight accommodations on the peninsula (301-822-1300). One can have lunch at the Robert Morris Inn for less than $10 or a complete dinner, with drinks, for an average of $20 a person (301-226-5111). Lunch at The Tidewater Inn runs from $5 to $10 a person; at dinner, entrees are from $10 to $40 (for Chateaubriand). Both establishments offer lodgings. Overnight rates at the Robert Morris run from $27.30 for a very basic room to $70, with $42 average for a double. At the Tidewater Inn, rooms cost from $38 for the least expensive single to $58 for the most expensive double. Two Detours After a night's rest, southbound seafood mavens may want to make two short detours - to Crisfield, Md., for a softshell crab lunch; just to the south off U.S. 13, to Chincoteague, Va., the site of the Assateague Island National Seashore, with its longlegged cranes in a roadside wildlife preserve and its marvelous dunes. The Halfway Mark From an Oxford-Easton layover, lunch could lie ahead (by U.S. 50 through Salisbury, Md., and then U.S. 13-South) at the half-way mark toward Cape Charles and the bridge-tunnel to Norfolk. At Wachapreague - and worth the short detour off the highway - there is The Island House (804-787-4242), with lunches for under $5. The Island House offers two weekly dinner specials at $4.95 and $6.95, as well as entrees ranging from $6.25 to $10.95. And if there is time for dinner in Norfolk after leaving the bridge-tunnel, scan the map for the community of Ocean View near the Norfolk Naval Air Station (U.S. 60-West after regaining dry land), or stop and call Lockhart's Restaurant (804-480-3024 or 804-588-0405) for directions. Lockhart's is open for dinner only, with complete meals at $5.95 to about $16. By Norfolk standards, Lockhart's is an unusually gratifying find. Thence by I-64 or I-264 to U.S. 58 and the resumption of I-95 South. Ben A. Franklin