A unique water mass in the East Sea
Off the coast of Sokcho, a unique body of water called the East Sea Proper Water (ESPW) provides a resource with distinct physical and chemical properties. This water mass is cold, stable, and pure. Commercial operations pump this water from depths ranging from over 510 to 605 meters. At these depths, the water temperature remains a constant 1-2°C throughout the year. Because sunlight cannot penetrate to this "aphotic" zone, photosynthesis does not occur, which severely limits the presence of microorganisms and keeps the water free from surface pollutants.
The East Sea Proper Water is a semi-isolated mass that forms within the East Sea (Sea of Japan). It is largely independent of the intermediate and deep waters of the North Pacific. Its formation is a complex process linked to surface cooling and sea-ice formation in the northern parts of the sea, which creates denser water that sinks and fills the deep basins. This deep water has a low temperature, high purity, and a specific mineral profile that differs significantly from surface water. The water is high in dissolved minerals and nutrients like nitrates and phosphates because they are not consumed by plankton in the dark depths.
A specific mineral balance for industry
The most commercially important feature of Sokcho's deep sea water is its mineral balance. It contains a consistent ratio of magnesium (Mg), calcium (Ca), and potassium (K) of approximately 3:1:1. This ratio is noteworthy because it is similar to the mineral composition found in human bodily fluids, such as amniotic fluid. This characteristic is the basis for its use in the cosmetics industry, where products claim the mineral balance allows for rapid skin absorption. For example, one moisturizing cream uses 60% deep-sea water sourced from 605 meters deep in Gangwon Province.
This deep water is also a resource for aquaculture. The cold, stable temperature and high purity are ideal for farming cold-water marine species. Land-based aquaculture facilities in the region are being developed specifically for the East Sea to cultivate high-value species that thrive in these conditions, moving away from coastal areas more susceptible to temperature fluctuations. Beyond cosmetics and aquaculture, the water is desalinated and sold as premium bottled drinking water and used to make specialty food products, including tofu and salt. One company in Sokcho has a water intake capacity of 30,000 tons per day to supply these various industries.