Sand is probably the most effective seasoning known to man. Take the lowest mean-spirited pizza or the sleaziest hot dog, and serve it on the beach to turn it into manna. Sun, sea and warm oily bodies incomparably garnish picnics that otherwise would enjoy only an unsavory reputation.

So the wonder of wonders is not that boardwalks sell so much degenerate food. After all, when have businesses served the public better than the public asked for? The wonder is that some highly edible food comes from boardwalk vendors. Unlike the interstate highways, the footwalks - if Ocean City is a representative sample - serve food of character, a native cuisine worthy of investigation.

This investigator combed the boardwalk of Ocean City, Md., from beginning to end in early May, while painters and carpenters outnumbered tourists, for a preseason taste of summer to come.

A first look establishes the comfortable assurance that nothing has changed. There are still ten pizza parlors within a ten-minute stroll. The clouds of grease still perfume the salt air. Yet there are tendrils of modernity (admittedly the kind of modernity that is a solid five years behind everywhere else). The Potato Shack has gone contemporary, branched out from french fries to "Gourmet baked potato with toppings." Creeping chocolate chip cookieism has slid down from Boston through Atlantic City to Ocean City. Vietnamese cha gio have been rumored though not actually spotted.

But boardwalks are one of the few phenomena one can deal with systematically. We can start at a definite beginning, in the shadow of the haunted house and carnival rides, work our way up the walk until satiety and residential zoning coincide. If you don't mind interspersing fried chicken with ice cream, the boardwalk has a beginning, a middle and an end.

Dayton Brothers, at S. Division Street and another branch farther along the boardwalk, is the Charles Atlas of boardwalk concessions, boasting "World's Finest Chicken and Sandwiches." Wrong. But not dead wrong. The chicken - fried, it is - crunches and oozes and drips as one hopes fried chicken will do. It costs 55 cents a piece, $4.50 for a bucket of eight, and teams well with a pickle-packed homemade potato salad. But this is summer, when the only sin is not eating enough softshell crabs, and an impeccable fried soft crab on a big spongy roll costs $2.35. Let that begin your beach vacation.

Then there is Thrasher's, which is all some people know about boardwalk food, and all one needs to know if french fries are as important to your life as they should be. Fresh cut, fried in peanut oil. What's a summer day without a french fry?

Over the Oceanside Chicken stand at Wicomico Street is a Morbid Manor haunted house sign promising "A new experience in horror." No relation. Oceanside Chicken is a new experience in nothing. Its chicken is a bit cheaper than Dayton's (nine pieces for $4.50) but a shade less crisp and more soggy, lightly crumbed and adequate but no threat to anybody. Even the counterperson warns against the frozen crab cakes.

Sherbet may be the traditional way to clear one's palate between courses, but Boardwalk Daryland at Worcester Street presents good reason to pause with ice cream between the fried chicken and pizza courses. The ice cream is said to be homemade, comes hand-dipped or sift-swirled. And Pina colada, with bit chunks of fresh pineapple and shreds of coconut, has loosened my decades-long loyalty to the Brigham's mocha almond of my Boston youth.

No, I have not found the perfect hoagie. But I have found another that can keep me alive during my search. The Alaska Stand, with branches at Wicomoco Street and at 9th Street, makes it haogies to order ($1.95 and $2.45), with certain esoteric touches serious students of hoagie art will appreciate. The Italian cold cuts and cheeses are satisfying quality, and the lettuce, tomato, onion and hot peppers are well-sprinkled with oregano. But most important, the meats are layered on top of the salad stuff so they envelop the stuffing and hold it in while you bite. Good structural effect. The roll is toasted, warm, chewy, thus achieving the greatest potential an average hoagie roll could hope to achieve. Don't get sweet-talked into the french fries.

All this has been prelude to pizza. Boardwalk pizza is portable, indestructible, unobjectionable. And sand wipes off it easily. Lombardi's pizza, at Wicomoco Street and at Talbot Street, looks like every other slick, flexible slice of pizza you have ever encountered. But it tastes a lot better. Its crust is crisp and chewy. Its cheese stretches into long threads. Its puddle of tomato is well-seasoned. It costs 60 cents a slice (75 cents with pepperoni), and is as good a pizza as I have found sold by the slice.

It is not meant to be a Polish joke, but the one thing not to order at Polack Johnny's (at Dorchester Street) is the Polish sausage, also known as the "unburger." It comes on a hot dog roll. It is slathered with a super sauce of onions, ketchup, relish, Tabasco, celery and hot peppers. It is a wonderful slurp of a sandwich except for that greasy tasteless sausage it is meant to glorify. Try it instead on an all-beef Big John (95 cents). Drink with it a glass of honestly fresh lemonade. The ranch fries are said (by the counterperson) to be good, freshly cut potatoes with the skin on, floured, spiced, and fried in peanut oil. But neither they nor the breakfast Muffinski were available for inspection.

General's serves its breakfast all day, but not the day I wanted it. I would return, too, for the fresh melon drinks at the taco stand. But, as luck would have it, I was a prisoner of Pizza. The rest of the pizza I tasted just reinforced my devotion to Lombardi's. Tony's pizza at Division Street is a hard, dull, sullen slab. And you can't even get it with pepperoni by the slice. Freddie's Italian Food at 9th Street, however, keeps several pizzas in the warmer in case somebody comes along who wants one. I didn't. Ocean City's boardwalk makes a subspecialty of cannoli, and Freddie's cannoli ( $1) are pretty things, freshly filled and sprinkled with confectioner's sugar. But they taste as if they are filled with sweetened white sauce rather than ricotta.

Julia's Pastry Shop at 11th Street, on the other hand, could start a cannoli ground-swell. Shell as fragile as a sand castle. Filling piped in at the last minute and sprinkled with chocolate. A mine of sweet-tangy ricotta with chocolate chips and wispy scents of orange and cinnamon. Julia's also makes eclairs and cookies and brownies and all the other bakery standards, but her heart is in her cannoli.

More is to come. Enriqueta's Mexican restaurant in Georgetown is spawning an boardwalk branch. Potatoes are being peeled on block after block.Smorgasbords shout their ever-lower prices (down to $2.49) and ever-greater variety (up to 200 items). The tides of crab cakes and frozen yogurts roll in through June, July and August, then roll out to make room for next year's sea of get-it-while-it's-hot-and-eat-it-when-it's-cold-and-sandy boardwalk food. CAPTION: Picture, no caption, by Bill Snead