Where cold and warm
currents meet
Where cold and warm currents meet.
Korea is a four-season transition zone where cold and warm currents meet in a single sea. Unlike the “warm, consistent seas” of Sipadan, Raja Ampat and Cebu, Korea is a changing sea whose marine life and water temperature shift with every season — adding territory, culture and city access on top.
Korea's largest colony
of endangered coral
At about 25 m depth off the west of Dokdo's Seodo islet, the Class II endangered wild species hard coral (Dendrophyllia cribrosa) forms Korea's largest single-species colony here. Measuring 5 m wide and 3 m tall, the Ministry of Environment officially announced it as “the nation's largest single-species habitat.”
Korea's first
marine Natural Monument soft-coral garden
Jeju's coastal soft-coral colony is Korea's first marine-life Natural Monument (designated 2004, about 90.1 km²). Legally protected anthozoans alone number 13 species across 4 orders, 9 families and 11 genera. At Munseom alone, over 60 species of coral and subtropical life such as yellowtail amberjack and sea turtles spread along the volcanic walls.
An undersea seamount where
cold and warm currents cross
Wangdolcho is an undersea seamount where the North Korea Cold Current and the East Korea Warm Current cross. Cold-water, warm-water and open-ocean species mingle in one place — “the East Sea's finest golden fishing ground.” A 2006 survey by the Ministry of Oceans and Fisheries confirmed a remarkable 126 species.
Wangdolcho dive siteA changing sea,
the world's fastest warming
Korea's coastal waters are warming more than twice as fast as the global average. Over 57 years surface water temperature rose +1.58℃ (the East Sea +2.04℃), and isotherms shift 47.5 km northward each decade. Warm-water fish such as yellowtail and Spanish mackerel are surging in the East Sea — “a sea on the climate-change frontline.”
The East Sea Stella wreck,
an artificial reef sunk on purpose
At Gangneung Underwater Park, the roughly 2,474-ton Russian trawler the Stella (about 62 m, at roughly 30 m depth) — deliberately scuttled as an artificial reef in 2020 — forms a huge artificial reef together with an armored vehicle. It is not an accidental wreck but a wreck sunk from the outset for divers and fish.
Volcanic Jeju Island,
beginner-friendly + city access
Jeju is a volcanic island in the Korea Strait. Soft-coral gardens drape lava rock, sheer walls and caves, so everything from shallow beginner bays to deep walls sits on one island. Beginners and advanced divers alike can enjoy it, with the city access of reaching it from Seoul by KTX or domestic flight.
- Winter cold & access limits — the East Sea bottom drops to 2–4℃, requiring a drysuit, and 3–5 m winter swells restrict boat departures at Ulleung and Dokdo.
- Variable visibility — visibility drops during the summer plankton bloom. Clearest in spring and autumn.
- Ulleung/Dokdo “year-round 30–40 m visibility” is unconfirmed in exact meters — we state only “Korea's clearest waters (qualitative).”
- This content uses only facts confirmed in deep-research verification (19/25 confirmed) and excludes refuted items.