Shum Mei-ying, 22, had gone through an abortion, a seven-day hike during a typhoon and a one-mile swim across shark-infested waters to escape China and join her husband here.

She was semiconscious, paddling desperately with the help of fellow female escapee Tang Shui-ling, when - just in sight of Hong Kong's shore - all hope vanished. The marine police, under orders to send all refugees back to China, chugged up in a launch and picked the two women out of the water.

Shum and Tang were part of sudden influx of illegal and legal immigrants from China that has crowded the railways and waterways into this British territory. As many as 70,000 Chinese may enter Hong Kong this year, the largest number since 1973 and, ironically, a measure of how some aspects of life in China have improved recently.

"We've found in the past that when legal immigration increases, illegal does too," said Henry Allen, director of the privately funded International Rescue Committee office here. "More legal exit permits means a relaxation of government policy, and that relaxation goes right down to the basic level," making illegal escapees more confident that no one will try to keep them from leaving.

Through August, 35,148 Chinese have entered Hong Kong holding legal exit permits from the Peking government. This is double the number of legal immigrants for the corresponding period last year and has led the British government to make repeated appeals to China for some relief from the unusual load.

Any sudden increase of immigration severely strains the already over-loaded housing and welfare facilities for the 4.4 million people stuffed into the 400 square miles of territory here. The number of legal immigrants dropped slightly from 5,705 in July to 5,665 in August but the rate of about 150 a day is considerably above the rate of 50 or 60 a day that the two sides appeared to agree on after the last immigration flood in 1973, also a year of relatively relaxed government policies in China.

Almost all the legal immigrants have relatives living outside China, which is the key to Peking's sudden liberal attitude toward exit visas. The Communist Party has decided it needs the support of ethnic Chinese living abroad, both to isolate its Nationalist Chinese rivals on Taiwan and to gain the technical and commercial expertise many overseas Chinese might want to share.

Relations between China and British-ruled Hong Kong appear to be at an all-time high. The Chinese have bent over backward to assure the British that they have no intention of taking over the territory.

But the government here realizes that it exists only on the suffrance of the Chinese. It can do little more than make polite protests about Chinese policies it does not like, such as the suddenly increased number of exit permits. Refusing to accept immigrants with bona fide Chinese documents would be unthinkable.

As for the illegal refugees, the government has worked out a few informal rules that appear to suit both sides. Any illegal refugee apprehended by Hong Kong police in the act of crossing the border will be returned to China. A refugee who reaches the colony's urban areas without being caught almost always will be allowed to stay.

One of the successful migrants, it turned out, was Shum Mei-ying, the woman who was fished out of the water last month by marine police. She was trying to join her husband, a laborer who made it here in April after seven previous unsuccessful attempts.

Like most of the immigrants, Shum and her husband, Chan Chow-sum, wanted to escape a life of low wages and dreary farm labor in China. Many also seek relief from the restrictions on freedom of movement and expression, although this seems less important to most refugees than the chance to make more money in Hong Kong.

That dream of a better life, and the need to rejoin her husband, led Shum to undergo an abortion. The pregnancy which began shortly before her husband left China would have reduced her chances of reaching Hong Kong. Her story made the newspapers here after she was caught. There were several appeals to the government to let her stay. Finally the authorities relented on "humanitarian" grounds.

Her friend Tang, who kept Shum from drowning as do many refugees, was not so lucky. Tang was turned back to the Chinese authorities but she probably will try to escape again.