In the shadow of a snowswept mountain range where the naked ice meets the sea, three Emperor penguins, movie stars of the Antarctic in their black and white get-up, waddle into the distance. Mournful seals, suckling fat pups, sun in the dazzling light. Skuas careen overhead, their dark wings spread against the sky.

Just under the surface of the water, vast swarms of krill, tiny shrimp with the extravagant scientific name of "Euphausia superba," are visible from satellites. They color the ocean pink in summer, and, in the winter night, light up the shoals with waves of blue-green phosphorescence.

This is the great southern ocean, home of the humpback whale and mother of all Antarctic wildlife. It is one of the curious marvels of the planet that the most barren of continents, where the largest inland creature is a wingless fly, is enveloped by one of the richest marine ecosystems in the world.

Today this remote region at the bottom of the earth is becoming the focus of an intense international battle over resources. Krill, which has the protein equivalent of beefsteak, is the world's largest undeveloped fishery. Just off the icepack, large stores of petroleum, estimated in the tens of billions of barrels, may lie buried under the continental shelf. Even the continent's reserves of iron ore, coal and other metals might someday be developed.

The 13 nations that administer the Antarctic under a 1961 treaty are faced with the classic dilemma: exploit or preserve. At stake is the biggest wilderness in the world, 5.5 million square miles of virgin territory hardly touched by the polluting hand of humans.

Last May in Canberra, Australia, the United States and other nations signed an agreement to set up conservation measures for krill, which is being fished by the Soviet Union, Japan and other countries. That convention was the first step toward a mineral-development agreement that will begin to be negotiated in Buenos Aires this year.

On a ridge overlooking the vast ice shelf here, Gisela Dreschhoff, a University of Kansas geologist, climbs into a helicopter and heads for the mountains, where she will aim her spectrometer at the outcroppings below. The machine, measuring radiation, can detgect uranium and other potentially valuable rocks.

"It would be wrong not to know what we have," she said. "This gives the U.S. a stronger position to negotiate from." Nonetheless, like many of the scientists who have operated here during the last 20 years, Dreschhoff is less than enthusiastic about development. "I want to see Antarctica as a laboratory and nothing else," she said."This is the last continent on earth that is untouched. I'd like to keep it that way."

The Antarctic treaty, drafted in the midst of the Cold War, sidestepped the territorial claims of rival nations, and, in an extraordinary feat of international diplomacy, dedicated the continent "in the interest of mankind" as a scientific laboratory, free of armies and weapons.

But 20 years ago, no one foresaw that this ice-locked land might be useful for anything else. Today nations that signed the treaty in spite of their territorial claims are reasserting rights to the spoils. Seven countries claim slices of the continent: Argentina, Chile, Britain, New Zealand, Australia, France and Norway. The other members of the "Antarctic Club" -- the United States, the Soviet Union, Japan, Belgium, South Africa and Poland -- do not recognize the claims.

If claimants and nonclaimants cannot agree on who owns the oil, the treaty could collapse and, along with it, a unique experiment in international harmony. Most experts, however, are confident that a system for sharing the wealth will be worked out.

James N. Barnes, a rumpled young lawyer at Washington's Center for Law and Social Policy, has never seen the beauties of Antarctica. To go there, one must be invited by one of the governments operating scientific bases on the continent. Barnes is no favorite of the diplomats who fashion Antarctic policy.

Working almost single-handedly out of the center's cluttered offices in an N Street town house, Barnes organized a group of 100 organizations in 20 countries to call for a moratorium on mineral exploitation, strict quotas for the krill catch and the creation of an international park.

"Antarctic ecosystems appear to be so fragile that any exploitation activities would produce adverse effects, many of which would be severe and virtually irreversible," B arnes and other environmentalists wrote President Carter in April 1979. Carter ignored the group's suggestion for a "World Preserve," and there is little hope that the Reagan administration, intent on energy development, will pay heed.

Besides the pressure of enviromental concerns, Antarctic nations are feeling the hot breath of the Third World. U.N. officials have periodically called for a sharing of the continent's resources as "the common heritage of mankind," a principle established in negotiations over the seabed wealth. Some development experts say it is only a matter of time before Antarctica becomes part of the North-South debate.

"It is very unlikely that the existing acquiescence of the international community will continue once resources begin disappearing," wrote Barbara Mitchell and Lee Kimball, two researchers for the London-based International Institute for Environment and Development, in an article in Foreign Policy magazine. So far, the "club" has managed to keep other nations from meddling by requiring large scientific expenditures as the price of membership.

Whatever happens to krill and oil, this wouldn't be the first time that Antarctica has been exploited. The continent was discovered by 19th-century sealers in search of fur. Once fur seals were hunted to extinction, whalers came from as far away as Nantucket and nearly wiped out the world's population of great whales.

Some fisheries experts predict that more than 100 million tons of krill could be harvested each year without depleting the stock. That would more than double the world's fish catch, and make krill the world's largest single natural source of protein. Some experts, however, doubt that there is much of a market for krill paste, sandwich spread or beer, the main products so far. o

Environmentalists contend that even the projected harvest of 2 million to 5 million tons a year during the next decade could endanger the ecosystem. "Krill is the foundation for everything in the Antarctic," Barnes said. "Penguins, whales, fish all eat krill. Humans will go after the same swarms as endangered whales. Even a small harvest could mean the death of the blue and humpback whales."

The humpback, the blue and other near-extinct species migrate to the southern ocean each summer to gorge themselves on krill before they go north to fast and breed in warmer waters. A blue whale can devour up to five tons of krill a day.

U.S. diplomats say the new convention on marine life, to be voted on by the U.S. Senate this year, will safeguard whales and other wildlife through its innovative "ecosystem" appraoch, the principle that the krill catch should be restricted, based on its effect on other living creatures.

However, in a tradeoff to prevent claimant states from invoking 200-mile limits, thus opening a Pandora's box of ownership issues, no national catch quotas were set.

Without quotas, and without a substantial research program to determine the amount of krill and its place in the ecosystem, "There can be no substantial optimism that the new convention will work," Barnes said. A comprehensive wildlife monitoring system could be set up, he added, if each nation contributed $20 million -- "the equivalent of one fighter plane." The United States currently spends about $9 million a year for Antarctic research and $54 million to run the bases and provide logistical support.

This summer, Japan sent a 1,000-ton vessel, the hakurei Maru, to the Antarctic to begin a systematic petroleum survey. Based on four holes drilled by a U.S. research ship in 1972, which discovered ethane and methane -- indicators of oil -- the U.S. Geological Survey estimated that there could be so much as 45 billion barrels of oil and 115 trillion cubic feet of gas off Antarctica's coast. That would be five times Alaska's proven reserves.

U.S. oil companies are keenly interested, and it is no accident that two of them, Gulf and Exxon, are represented on the State Department's Antarctic Advisory Board. While the Soviet Union seems somewhat reluctant to move forward on a minerals agreement, either because it worries about the effect of oil spills on krill or because it is less oil-starved than western nations, the United States, has been pressing ahead.

However, Antarctica has the worst weather in the world. Tankers would encounter the infamous winds of the southern parallels known as "the Roaring 40s," "the Furious 50s" and "the Screaming 60s."

Giant icebergs, up to three miles wide and 1,600 feet deep, scour the seabed, spelling disaster for any rig or pipes in the way. Storage tanks and other onshore facilites would be placed on the 2 percent of the continent which is ice-free -- the same coastal areas where wildlife breeds.

The remarkable bilogical productivity of the southern ocean is partly explained by the fact that cold water holds more oxygen and carbon dioxide, the gases needed by plants for photosynthesis. The 24-hour-a-day summer sunshine here further spurs the growth of tiny organisms that feed krill, and results in an explosion of growth down the food chain. Mineral-rich Antarctic waters flow across the bottom of the world's oceans, nourishing marine life across the globe.

But oil degrades more slowly in cold water, and should a spill occur as large as the 1979 Gulf of Mexico blowout, which took a year to cap, it could turn large portions of the southern ocean into a biological desert.

Such problems make the economics of oil drilling dubious unless oil prices rise astronomically. "For a petroleum deposit to be economically exploitable in Antarctic conditions, it would probably have to rank in the giant or supergiant category," a CIA study concluded.

But if oil proves too risky a proposition, and if no one likes krill paste or krill beer, there still may be a profit to be made.

Saudi Arabia has financed several studies to see if icebergs could be dragged to the water-short Middle East. At a congressional hearing, Edward Todd, director of the National Science Foundation's polar programs, called them a "tremendous potential resource," noting that "a tabular berg one-half-mile long, one-half-mile wide and 500 feet thick holds fresh water that would be valued at $4 million in an arid area."