The other Jamaica. If you haven't explored the east end, you've missed the best of the `Princess of the Antilles'

THERE is more to Jamaica than crowded beach clubs and persistent hawkers of souvenirs. The less-frequented eastern end of the island is a wilderness of pristine rain forest, secluded beaches, and cool, pine-clad mountains. Jamaicans in the parishes of Portland, St. Andrew, and St. Thomas are friendly, their food is exceptionally good, and lodgings - ranging from magnificent to rustically acceptable - average only $36 for two per night (in summer). And the tourist population is sparser, quieter, than the throngs at Montego Bay or Dunn's River Falls. In short, just 90 minutes from Miami and for only $210 round trip, you can maroon yourself in a setting as exotic, remote, and fascinating as any in the tropics.

If you fly to Kingston and want to get off the beaten track as quickly as possible, you can rent a car at the airport (reserve in advance, because they're hard to get on arrival) and head for Pine Grove Hotel and Chalets, situated on a 90-acre coffee farm 18 miles into the Blue Mountains at Content Gap. The views here are truly exceptional, and hiking trails radiate from it.

You can trek or ride to such charming spots as Guava Ridge and Mavis Bank, Pompey's Hut, and Misty Valley - or, going partway by Land-Rover, right up to Blue Mountain Peak, where, at 7,402 feet, the profile of Cuba shimmers in the distance on sunny days. And this is just a scratch on the surface of trekking possibilities in Jamaica.

The best source of general guidelines is MAYA Hiking Centre, Box 216, Kingston 7, Jamaica; tel. (809) 927-0357. This is also the same address for the only trekking tour operator, SENSE Adventures.

By night, this cool lodge in the hills overlooks a distant, glittering capital. Sitting outdoors to the soft piping of tree frogs, you can savor the delicacies of Mrs. Marcia Thwaites's outstanding Jamaican kitchen. This is a popular, if small, weekend getaway for Kingstonians escaping the heat and noise of the coast, so do make reservations, at (809) 922-7654 or 922-2271.

But you don't have to hike to experience the enchanting beauty of the interior. Simply make the wild drive over the Ridge of the Blue Mountains from Kingston via Hardwar Gap (4,000 feet) and up to Buff Bay on the coast. It takes three to four hours, depending on your nerve.

A more sedate route, but equally stunning, is the A-3 through Castleton (which has a superb botanical garden on the banks of the Wag Water River) to Annotto Bay. Either way, by turning eastward along the north coast road toward Port Antonio, you now enter the greenest province of Jamaica, the jutting edge of the island which is forever swept by the rain-bearing trade winds.

Port Antonio's most famous attraction is a three-hour raft ride down the Rio Grande; but, famous or not, on a Memorial Day weekend we were poled down this wide, purling river with its 100-foot-high banks - alone. Tropical birds called from shaggy stands of bamboo, and our gentlemanly captain, Samuel Gay, sent us swimming ashore to collect wild rose-apples, a delicious fruit like hollow apricots with the faint aroma of a rose. Occasionally, vending rafts on the gravelly banks offered cold drinks.

The trip costs $33, including the fee for a registered driver to take your car from Berrydale, the starting point, to St. Margaret's Bay, where the river glides into the sea. You can raft by moonlight, too, which can be arranged by writing to Rio Grande Attractions Ltd., Rafters Rest, PO Box 128, Port Antonio, Jamaica, West Indies; (809) 993-2778.

Beyond Berrydale and farther south into the mountains are two curious settlements, Moore Town and Cornwall Barracks, inhabited by descendants of runaway slaves, the Maroons. Even today they are a semiautonomous People Apart. If you want to visit them, you should first contact the Port Antonio Tourist Board, so that the Maroon Leader, ``the Colonel,'' can be notified in advance.

The loveliest place to stay in Port Antonio is Frenchman's Cove, where a hotel and cottages nestle among 44 hilly acres of tropical garden by the sea. A clear river slides into the ocean via an azure cove, whose powdery beach is sheltered by tall, sea-worn cliffs. There's snorkeling over coral heads around the cove and at neighboring San San Bay. A double, without meals, costs $36 a night in summer and $86 in winter. The buffet dinner for two costs about $35, but the dishes are authentically Jamaican, and you can make requests; for us they prepared excellent curried goat. Call Gregg Weston at (809) 993-3224/3449, collect for bookings only.

Farther down the east coast, the drive to Manchioneal passes coves, wind-swept bluffs, and Amazonian ravines. You have the distinct impression that few tourists have preceded you.

Reach Falls, on a very tenuous track west of Manchioneal, is one of the most spectacular cascades in Jamaica, rivaling Dunn's River Falls for beauty and far outdoing it for misty solitude. A trail leads to a whirling blue pool at the base of the falls, and there is a cave you can swim to behind the veil of crashing water. The trees grow to a hundred feet and taller, and the crack of an ax must have disturbed the chirruping of jungle folk very seldom in the last several centuries.

In southeastern Jamaica, the town of Bath has the only available lodgings, where a government-run hotel offers rooms ($15 a night for two), food (an excellent native dish called callaloo), and runs a spa, where you can privately soak in the hot springs issuing from igneous rock above the Sulfur River.

In 1699 the British Government bought 1,300 acres of land around the springs and erected the hostel, which became the most fashionable resort of colonial Jamaica. Now it's rather rustic but fine for travelers who do not insist on five-star sterility. For information, you can write to Bath Fountain Hotel, Bath PO, St. Thomas, Jamaica.

Near Bath, along Jamaica's southeastern tip, a very rough little track follows the coast east of the fishing villages at Port Morant and through the hamlets of Old and New Pera. Getting there, you will pass stands of coconut palms denser than are found anywhere else, except possibly in the Philippines. At some point between Old and New Pera, if you just drive off the road and down one of the grassy trails through the cane fields, you will come to a vast, yellow beach stretching to an utterly unpopulated horizon. The open, grassy dunes make an ideal place for camping or a picnic, as long as you have all the needed provisions, because things like shops and restaurants are worlds away. Practical information

For information on Jamaica, contact the Jamaica Tourist Board, 866 Second Ave., New York, NY 10017; call (212) 688-7650 or your local travel agent.