Korea Strait

The Korea Strait is a vital maritime passage located in East Asia. It sits between the Korean Peninsula to the north and the Japanese islands to the south. Specifically, the strait is bounded by the southern coast of Korea and the southwestern Japanese islands of Kyūshū and Honshū. This body of water serves as a major connection point for several large seas. It links the East China Sea and the Yellow Sea to the Sea of Japan. This connection makes the strait a central part of the northwest Pacific Ocean region.

The physical structure of the strait is divided by Tsushima Island. This island splits the water into two distinct sections. The first section is known as the Western Channel. The second section is called the Tsushima Strait, or the Eastern Channel. These two parts have different physical characteristics. The Western Channel is narrower than the Eastern Channel. However, the Western Channel is also deeper, reaching depths of up to 227 meters. On average, the entire strait maintains a depth of about 90 to 100 meters.

Ocean currents play a major role in the environment of the strait. A branch of the Kuroshio Current flows through these waters. This warm branch is often referred to as the Tsushima Current. It originates near the Japanese islands and passes through the Sea of Japan. The current eventually flows into the northern Pacific Ocean or the Sea of Okhotsk. The water characteristics vary significantly throughout the passage. This variation occurs because of low-salinity waters coming from the southeast coasts of China and Korea.

Economically, the Korea Strait is a critical corridor for global trade. Numerous international shipping lanes pass through the strait every day. These lanes carry heavy traffic toward the major ports of southern South Korea. To support this trade, both South Korea and Japan allow free passage through the strait. Japan has even restricted its territorial waters to three nautical miles instead of the usual twelve. This decision reportedly allows United States Navy warships and submarines to transit without violating Japanese laws regarding nuclear weapons. Passenger ferries also provide essential connections between many different locations.

Commercial ferry routes connect several major cities and islands. Ferries run from South Korean locations like Busan and Geoje to Japanese ports. These Japanese destinations include Fukuoka, Tsushima, Shimonoseki, and Hiroshima. Other ferries connect Tsushima Island to Fukuoka. There are also routes linking Jeju Island with the Korean mainland. Some ferries even carry passengers between Japanese ports and cities in China. These routes demonstrate how the strait functions as a busy highway for people and goods.

The history of the strait is marked by significant cultural and military events. During the Pleistocene glacial cycles, the strait was much narrower. At times, the Japanese islands may have been connected to the Eurasian Continent. During these times, the Sea of Japan may have been a frozen inner lake. In the 6th century, the Baekje people used the strait to transmit Mahāyāna Buddhism to Japan. Later, in 1274 and 1281, Mongol and Korean fleets attempted to invade Japan. These invasions caused severe damage to Tsushima Island. In 1905, the Battle of Tsushima took place between the Japanese and Russian navies. More recently, the Battle of Korea Strait occurred in June 1950 during the Korean War. This naval battle resulted in a South Korean victory when a North Korean transport was sunk.

Looking toward the future, engineers and leaders have discussed new ways to connect these lands. One major proposal is the Japan–Korea Undersea Tunnel. This project would create a physical link between Japan and Korea beneath the sea. This idea is similar to the Channel Tunnel that connects France and the United Kingdom. While people have discussed this possibility for many decades, it remains a topic of debate. The strait continues to be a place where geography, history, and modern economy meet.