Every spring, on Karan Island and other empty patches of sand in the Gulf, the swift tern, a shy, noisy and lovely addition to the Gulf's known breeding species, comes to play, to feed and to raise its young.

Philby called it "the very backbone of Arabia" and Thesiger described its "graceful, laughing people." This is Asir - fertile, cool, and scenically magnificent.

"But surely" they say, "there are no butterflies in Arabia!" There are, though-no less than 130 species: some of them nomads in constant search for the plants they need to survive and breed.

This fall in Saudi Arabia, the government is opening its first national park - a $14-million, 1,000-square-mile preserve of soaring mountains, misty valleys, and falcons hovering in the wind.

Because the Red Sea is at once unique and vulnerable - to both spillage and spoilage - Saudi Arabia and other countries along its shoreline are taking steps today to save it for tomorrow.