He's tiny. He's healthy. He's 82. With wives who number more than three score, his progeny are multitudinous. He rules a land of peace and prosperity, beloved by his people. He has, you might say, all a king could want.

And today, King Sobhuza II, the world's longest reigning monarch, celebrated his diamond jubilee as ruler of Swaziland. Under sunny skies of southern Africa, the party was attended by approximately 60,000 Swazis. It was happy, festive, colorful, the kind of time all too rare on this troubled continent of refugees, strife, poverty and war.

It was a reflection of Swaziland. A landlocked nation of green valleys, waterfalls, and mountainous escarpment that is smaller than New Jersey, it remains an oasis of tranquility and harmony even though it is bordered on three sides by conflict-ridden South Africa and on the fourth by revolutionary Mozambique.

The country's success is attributed in no small measure to the lion, as Sobhuza is known to his 600,000 subjects. He urges them to think for themselves, taking what is best from both European and African cultures.

Today's ceremony, like Sobhuza's reign, was a mixture of Western and African styles. The king was transported to the soccer stadium in a long black limousine. He stepped out, barefooted and attired in the skin of a small leopard, onto a red carpet. Feathers of the sakabula bird, stuck in his hair, denoted his royal lineage.

A low whistle of praise from his subjects swept through the stadium like wind in the trees. Among the admirers were the royal family -- his wives and children, about 200 in all, filling a whole section of seats. Those keeping count say he has had 68 wives in his lifetime, many of whom have already died, and children who number about 150.

After inspecting an Army resplendent in fire engine-red blazers and navy-blue pants, the king led a regiment of spear-carrying Swazi warriors in a traditional dance.

Sobhuza was born July 22, 1899, and designated king by his tribe's elders the same year. He assumed power in 1921. By then, Swaziland has been a British protectorate for 18 years. It became independent in 1968 as a constitutional monarchy.

The British-modeled constitution disappeared in 1973 when Sobhuza abrogated it as "untraditional" after an opposition party made gains in an election. Swaziland got a new constitution in 1978 that outlawed political parties. The names of candidates for the House of Assembly are only revealed when the polls open. It is just an advisory body. Sobhuza rules with the help of his tribally based Swazi National Council.

His rule sometimes involves detention of political dissidents -- 13 were released last year and there are none at the moment. Sobhuza's style is anathema to most of Africa's educated elite, who see him as an anachronism on a continent enamored with the concept, though not necessarily the practice, of popular democracy.

But Sobhuza's rule appears to have worked for Swaziland. Because the Swazis are tribally homogeneous, they have been spared strife from that source. About 7,000 whites still live here from British days. The assembly has some white members, and whites still own a large percentage of land under long-term leases given out before independence.

The economy is dominated by sugar, which provides the bulk of exports. Swazis' average per capita income is $590. The literacy rate, 50 percent, is high for Africa.

The main reason for this relative economic success is Swaziland's close economic ties with South Africa. It is a member of the South African Customs Union, where it earns 60 percent of its revenue -- 90 percent of its imports are from the white-ruled country. Not surprisingly, Sobhuza has on several occasions opposed economic sanctions against South Africa.

Swaziland's compromise between African nationalism and its own economic survival is a bit more delicate when it comes to black insurgency against South Africa. Its official policy toward the black South African guerrilla movement is to offer sanctuary to genuine political refugees but not to tolerate the presence of armed men. But the country's strategic position inevitably makes it a conduit for guerrilla infiltration from Mozambique to South Africa.

This puts pressure on the tiny kingdom. In 1978 it expelled members of one of the movements after they attempted to set up bases here.

The most debated political question here is who will succeed Sobhuza and how. "They haven't chosen a king since 1899," said a foreigner living here, and "there is no one around who participated in the process." He described that process as "based on tradition, and tradition changed with the times."

But most observers believe the transition of power, to one of his sons chosen by the Swazi National Council, will be peaceful.

The kingdom is not immune to the forces that have undercut other monarchies -- urbanization, mass education, radical ideologies and government corruption. There is no detectable discontent at the moment but the country did experience a short outburst of student rioting in 1977.

These problems were forgotten this 60th anniversary jubilee.

Princess Margaret represented the British crown at the festivities. While addressing the Swazi Parliament yesterday, she said, to no one's surprise, that monarchy was the best kind of government.

Representing President Reagan was a delegation led by Air Force Secretary George V. Orr. Also attending were Deputy Assistant Secretary of State for African Affairs Lannon Walker and TV actor Don Defore, an active supporter of Reagan's campaign.

In a homespun homily, much as a New England grandfather might give his family on the porch when the night was hot, Sobhuza lamented how the world "is in a state of flux and confusion" because "the nations lack mutual trust."

One enthusiastic Swazi, asked what he thought about his king, offered a typical comment: "He's a perfect king. This is a land of peace. He'll last, maybe to a hundred years."