Florida's natural springs may not be eternal, but they're still keeping tourism hopes warm without consuming our vital energy resources.

Bubbling up daily by the millions of gallons of sparkling clean water (guaranteed to instill envy in the heart of any watcher of the polluted Potomac River), they provide residents and visitors alike with excellent opportunities for boating, fishing, swimming and sometimes scuba diving. Tennis and golfing facilities also are available in some areas, and anywhere in Florida one is never far from Atlantic or Gulf beaches.

A few springs have been commercially developed into important tourist attractions, featuring river cruises through fish-filled waterways lined with luxuriant foliage. The air is fresh and sweet-smelling; flowers radiate color; waterfowl; fly unmolested or paddle along nonchalantly; the protected and very-much-alive alligator - Florida's new "embassador of tourism" - cleverly imitates a floating log or a stuffed museum exhibit as it takes the sun, and sometimes there's even as underwater theater or gallery where you can see mermaids perform a ballet or fish feed.

All is green and quiet, and not one ill-mannered barking dog to fray a suburbanite's nerves.

I flew to Gainesville and then rented a car. (Competition is such in the Florida market that modest daily or weekly rates with unlimited mileage - you pay for gas and oil - is the rule. And often there's no "dropoff" charge, meaning you can pick up the car in one city and drop it off in another without additional payment.)

As soon as I headed south on Rte. 41, I began to glimpse another Florida, a part of the state those who limit themselves to the Gold Coast - the Palm Beaches, Ft. Lauderdale, Miami - or the Tampa-St. Petersburg and southern Gulf Coast areas never see.

It is a Florida of wide open pastureland, of sleek thoroughbred horses and stud farms, of well-fed cattle, tree farms, citrus groves, lakes, small towns, modest retirement homes, and slower-paced development. But to the motorist, at times it seems mostly miles and miles of well-maintained highways winding past cool woods - pine, oak or cypress restooned with Spanish moss - and those streams and rivers and springs providing fresh water that spells beauty and life.

Springs can be found in 46 of the 67 counties, according to the Florida Department of Commerce. The Sunshine State has 17 of the 75 "first-magnitude" springs in this country. In a first-magnitude spring, water flows at a rate of at least 100 cubic feet per second. The department notes that "the discharge of a single cubic foot of water per second is 646,000 gallons daily - enough to satisfy the requirements of a city with a population of 6,000."

There are also 49 springs of second magnitude, and still other smaller springs. Water temperature generally ranges between 68 and 76 degrees fahrenheit. Some are privately owned, thus permission to swim on dive must be obtained.

Two first-magnitude springs typical of the major attractions are Silver Springs and Homosassa Springs. The first, estimated to be 100,000 years old, was listed by the state in 1976, based on attendance figures, as Florida's fifth most important attraction - behind Disney World, Busch Gardens, Sea World and Cyprus Gardens. It draws about 1.5 million visitors a year, compared with more than 13 million at Disney's fantasyworld and 2.4 million at Busch.

Located six miles east of Ocala on Rte. 40, Silver Springs (the name refers to the nature/entertainment complex and the small town, population around 900) has attracted tourist for more than a century. This is the 100th anniversary of the first glass bottom boat rides at the springs. Hart Line steamboats carried the famous and not-so-famous of the 19th century up the Ocklawaha River to Silver River from Palatka. With the advent of the railroads and the demise of the steamboat, visitor totals declined, a trend that continued into the early 1900s. The interest picked up again.

In "Enternal Springs," a history of the area, Richard A. Martin observes that "the promoters of the Hart Line steamboats had proved one thing - that people liked their beauty spiced with excitement even in a natural attraction. Hart Line steamboats had provided the excitement . . ." Rand McNally's "Guidebook to Florida" notes sagely that "Floridians have learned this lesson well."

The good-natured hokum and the whipped cream that tops off outdoor activites at Silver Springs indicate that its owner and operator, ABC Leisure Attractions, Inc., belongs at the head of the class.

For an all-inclusive entrance fee ($5.25 for adults, $3.25 for children 3 tp 11, visitors can take a jungle cruise - the brochure claims that you will see "rhinoceros charging at your boat (stopping at the water line, of course)" - but the rhinos actually are safely separated from the waterway. Among other animals pointed out by the skipper-guide are giraffes, alligators, monkeys and birds.

Despite the obvious commercialization, Silver Springs covers 4,500 acres with most of the land in its natural state and unchanged for centuries. Only about 100 acres are presently "developed" and in use, but a spokesman said "the next five-year plan" being completed will provide for "increased usage."

The attraction is an official Florida fish and game preserve, protecting birds, reptiles and mammals that are members of endangered species. One member of the crocodile family, the gavial, which has long, needle-like jaws, is "already considered extinct," the park spokesman said, because there are less than 200 of them worldwide and that is an "insufficient number" to insure the survival of the species.

There are also shows at the Reptile Institute, a deerpetting area, a musuem featuring a collection of antique and classic cars, a garden of marigolds in memory of Sen. Everett Dirksen, and of course snack bars and the inevitable gift shop with the usual undistinguished merchandise.

A new, $1.7-million attraction, Wild Waters, whose touristy gimmick revolves around a pool with manmade waves and a series of flume rides, has just opened next door. A separate park that charges additional admission, it's also owned by ABC Leisure Attractions. That corporation, a subsidiary of the American Broadcasting Companies, Inc., also owns and operates Weeki Wachee on U.S. Rtes. 19 and 50 about 60 miles north of Tampa, another springs and wildlife park.

Weeki Wachee ("even the name is fun") offers, along with various animal performers and the requisite boat rides down the Weeki Wachee River, an unusual show in its underwater auditorium with a cast of "mermaids" who cavort in a natural cavern with the help of compressed air hoses. The current 30-minutes production, "Operation Mermaid," has "Waterwoman" battling "Sharkwoman."

And since competition for the discretionary dollar is strong and to stand still is to risk being bypassed by the motoring spenders, both home folks and out-of-towners, a new entrance plaza will open in August. It will complete a $3-million expansion that includes a Birds of Prey Arena (featuring hawks and eagles). Seven acres are developed out of about 450.

Homosassa Springs, "nature's own attraction," is sighted through the windshield seven miles south of Crystal River on Rte. 19, 75 miles north of Tampa. Source of the Homosassa River, it attracts both fresh and salt water fish of many varieties.

Though it's possible to drive directly to the center of the Park, a more pleasant introduction is the 17-minute cruise from the main entrance and dinning room on 19 along a peaceful waterway that winds through woods. Along there are the animals - monkeys, deer, a hippo; flamingoes, peacocks and waterbirds, and an underwater observatory. There arealso sea lions, crocodiles and the ubiquitous alligators.

A copyrighted caricature of a gator named "Ollie" was created recently by Walt Disney artists to serve as ambassador of Florida tourism as a logo, and in costume "in person" at travel shows, festivals and other events. "He makes you feel happy, and he's a perfect symbol of Florida as a family vacation destination," said state tourism director Bob Whitley.

But it is only necessary to see "Ollie's" powerful tail whip around, his deceptively langorous body leap into the air, and his toothy jaws yawn wide to snap viciously at tidbits during feeding time, to recall that he is a dangerous animal that can kill swiftly and horribly. Small children must be watched carefully to make sure they do not attempt to climb over fences.

I think Homosassa is a bit lower keyed - perhaps it's also the smaller scale compared to Silver Springs. Admission: $4.25 adults, $2.10 children 5 to 15. I enjoyed the nature walk, the live oaks, the sabal palms, the silence. The more secluded Riverside Villas resort, which has a marina, and the newer and attractive but (for my taste) less desirably located Sheraton Inn at the main entrance, are good places to spend a few relaxing days.

It's wise to remember that temperatures in northcentral Florida can drop below freezing in winter, and even in April the weather may be a bit brisk at times. Come in summer if you want a better chance of staying warm.

I spend two days at Crystal River's Plantation Inn, using the 100-room resort off Rte. 19 at the edge of King's Bay as a base for forays into the surrounding area.

The two-story inn offers estate-like grounds, a pool, golf, tennis, fishing in spring-fed waters off its seawall (you can see the fish swimming in the clear but vegetation-filled canals) or in the Crystal River - boats are rented at the adjoining marina and can be charged to your room.

Plantation describes itself as "a pleasant and welcome departure from the steel and concrete boom of highrise hotels dominating so much of Florida's coastline." Horizontally spread out, it has plain, large, pleasant rooms (cheapest $26 single or double, without meals), a friendly staff, and a dining room that provides excellent service and tasty food at moderate prices. The only sour note during my stay was caused by lack of soundproofing in the frame structure and some noisy guests.

This area calls itself the "West Citrus County Suncoast Springs . . . an outdoor paradise." Perhaps that's not too much hyperbole for so much greenery and clean air and water. The spring-fed Crystal, Withlacoochee and Chassahowitzka Rivers, among others, are a powerful draw for experienced anglers. And tens of thousands of scuba divers head for Crystal River each year, since the springs here provide some of the best diving sites north of Palm Beach and the Keys.

On an educational note, visitors should set aside some time for the Crystal River State Archeological Site a short distance off Rte. 19. Bordering the river, the area was an Indian ceremonial center for about 1,600 years, beginning before the time of Christ. It is rated by the Florida Department of Natural Resources as "one of the most . . . important pre-Columbian Indian sites" in the state.

While it is not spectacular, it is well maintained, and the view of the river from atop one of the mounds may make you pause and consider what it must have looked like to the Indians who lived and died there so long ago. Evidence unearthed indicates there was trade with Indians north of the Ohio River and connections with the Indians of southeastern Mexico.

Eastern Airlines (now celebrating its 50th anniversary) flies to Gainesville via Atlanta. National Airlines (which has just inaugurated non-stop service from Miami to Frankfurt and Amsterdam as part of a new European schedule), offers flights to Jacksonville. Or take Amtrak, the bus - or drive all the way if you have the time and the fortitude.