Korea consists of a mountainous peninsula and 3,201 contiguous islands. It is separated from Manchuria by the Yalu River, Mt. Paektu and the Tumen River. The Tumen River separates Korea from Siberia at its mouth. The Korean peninsula is flanked by two oceans, the East Sea to the east and the West (Yellow) Sea to the west. It lies between 124.11 degrees and 131.52 degrees East Longitude and between 33.06 degrees and 43.1 degrees North Latitude in the northern temperate zone of the Eastern Hemisphere. The standard time is based on the meridian passing through the center of the peninsula along 135 East Longitude. The total area of Korea is about 221,000 square kilometers — 99,173 square kilometers in South Korea, 122,827 square kilometers in North Korea. The longest distance in the peninsula from north to south is 600 miles, and the average distance from west to east is 170 miles.