3. Name one body of water that borders the USSR?
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I think is

Explanation:

Caspian Sea,

Most prominently they included the Caspian Sea, the world's largest inland sea, and Lake Baikal, the world's deepest and most capacious freshwater lake. Lake Baikal alone held 85 percent of the freshwater resources of the lakes in the Soviet Union and 20 percent of the world's total.