Lynne Cox, who has swum every significant...

Lynne Cox, who has swum every significant saltwater strait in the world, including the Bering Strait between the United States and the Soviet Union last August, plans next to swim the Soviet Union’s Lake Baikal.

The lake, located in Siberia a mile above sea level just north of Mongolia, is 400 miles long and varies in width from 18 to 50 miles. A mile deep in some places, it is beset by strong winds, and the water temperature seldom rises above 50 degrees.

Cox, 31, of Los Alamitos, said Friday she hopes to make the attempt in August. “It’s going to be the hardest swim of all,” she said.

The Soviets agreed to let Cox make some significant swims in their country after she had swum the Bering Strait. She had discussed doing a series but was informed a few days ago by Vjacheslav Gavrilin, deputy chairman of the Soviet Sports Committee, that they would prefer she attempt only Baikal.

“This is going to be a 10-to-12-hour swim, at best,” Cox said.