JUST to float in a raft down this river in the hinterlands of Northeast Asia would not be easy, even for a Huckleberry Finn. The sand bars are as wide as the water that flows in this oversized creek.
Yet during the last two years, six nations with about one-third of the world's population have talked of turning the Tumen River into the nucleus of a new economic region, as if it might be another Rhine or St. Lawrence Seaway, a channel of commerce and civilization.
"Maybe another Hong Kong can grow here," says Wang Yusheng, deputy president of China's Asian-Pacific Institute.
Such dreams rest not so much on the Tumen's size as on its central location in Northeast Asia. This region, once rife with wars, could blossom with trade if the nearby nations warm up to each other in a post-cold-war world.
"If it had not been for the conflict and strife in this area during the last century, Northeast Asia could have rivaled the European Community as an economic power," claims Prof. Cho Lee Jay, vice president of the East-West Center in Honolulu.
The delta of the 360-mile Tumen River serves as a boundary between China, North Korea, and Russia. The river itself flows into the Japan Sea (known as the East Sea to Koreans). The ports of Niigata in western Japan, Pusan in South Korea, and Vladivostok or Nakhodka in the Russian Far East are all within reach.
Regional planners and scholars have been studying how to take advantage of the geographic proximity of these ports. Most of the port cities have been under-utilized "back doors" to their respective nation's economy during the cold war.
These planners point to the potential of combining the massive resources of Siberia, the cheap labor of northeastern China, and the technology and capital of Japan and South Korea. Land-locked Mongolia, too, is eager to use the Tumen as a trade outlet.
At various conferences, the six nations have moved closer on regional trade. "It's a long process to get these countries to sit down at one table," says Mark Valencia of the East-West Center. "What we are trying to do is to build a community. It takes a lot of kicks of the can to get it down the road."
The United Nations Development Program has designed the most elaborate plan for the Tumen region. The idea, says UNDP engineering consultant Aage Holm, "is based not on existing conditions but on future possibilities." A rough-guess cost for infrastructure in the Tumen area, he says, is $30 billion.
"This is not a crazy dream. It's absolutely possible," Mr. Holm stated at a conference of Tumen-area advocates in North Korea's capital this month.
The fact that communist-run North Korea opened its doors to such a conference, allowing about 145 Japanese, South Koreans, Americans, and others to visit the Tumen River, is seen as an example of how once-icy regional relations are quickly melting.
"This area has been like a big black hole," Holm says, "but now all the nations have opened it up ... and are trying to create special economic zones."
At best, Dr. Cho notes, talking about trade and investment in Northeast Asia will help prevent a resurgence of historic antagonisms. Mrs. Wang say six nations "now have a common understanding that the Tumen River area is very important to us."
China's border along the Tumen, for example, extends to within 12 miles of the Japan Sea, leaving it just shy of having a seaport there. China lost this strip in an 1860 treaty with Russia.
At the point on the river where the three former communist nations meet, there are few clues to the ties they once shared. A watchtower on Chinese territory looks out at both a Russian military base and North Korean farmland, where electric fences keep either intruders out or North Koreans in.
"Even though these nations are socialist, they don't trust each other," Cho says.
A railway bridge, built in 1958, crosses the river at this point, bringing Siberian coal and timber to North Korean ports for export. For a ship to sail up the Tumen and reach China would require either raising or razing the bridge. The river itself would take massive and constant dredging.
In addition, both North Korea and Russia appear reluctant to give access to China, preferring to draw foreign investment to their own nearby ports.
Last December, for instance, North Korea declared Chongjin, a port south of the Tumen, as a special economic zone, and anther nearby port, Najin, as a free-trade port.
This unusual welcome to capitalists shows how much closed, Stalinist North Korea is in need of hard-currency to pay for oil imports since the end of Soviet aid last year. Potential foreign investors, however, remain wary.
"Our investment environment will be no worse than other trade zones in Asia," says Kim Sung Chik, vice chairman of North Korea's committee on external economic cooperation.
Both North Korean ports are heavily guarded. A poster in Najin warns workers to watch for foreign spies. In Chongjin, recent foreign visitors were closely watched by soldiers with machine-guns and city residents were kept away.
UNDP consultant Holm says the Tumen scheme might "slowly bring North Korea into the real world. Perhaps if they open up, it will change their perception."
To get sea access on the Tumen, China proposes a multinational body to control the Tumen region, with the aim to create a "Greater Golden Delta." But North Korea, despite its dependency on Beijing for aid, insists on national sovereignty.
South Korean investors appear concerned about the high cost of someday absorbing the poorer north. Many want to develop the northeast ports and river to boost North Korea's economy, and to beat Japanese investors.
"I hope South Korea will be the first to invest," says North Korea Vice Premier Kim Dal Hyon, "because they are our compatriots."