West Sea
A sea opened by the tides. Large tidal range and strong current, low visibility over mudflats. Diving happens only in the narrow window around slack tide, at offshore uninhabited islands. A region for experienced divers.
Gyeokryeolbiyeoldo · Sibidongpado
The sea opens only at set times
In the West Sea, where the tidal range is large, strong current means danger. Safe diving is recommended only in the slack-tide window of small-tidal-range days — the narrow moment when the water briefly stops moving.
Leaving the mudflats
for offshore islands
The coast is mudflat terrain where visibility is hard to secure, so diving mostly takes place at slightly distant offshore uninhabited islands (such as Gyeokryeolbiyeoldo in Taean and Sibidongpado in Gunsan). Being far offshore with no scheduled ferry makes access and rescue difficult; while some zones allow legal seafood harvesting, legal diving through a resort or center is recommended.
A sea ruled by currents
Slack-tide diving
Safe diving only around slack tide, when the water stops moving.
Strong current
Strong current driven by a large tidal range — mainly for experienced divers.
Low visibility
Coastal mudflats blur visibility, so diving is done at offshore islands.
Offshore uninhabited islands
Slightly distant uninhabited-island sites are the heart of the diving.
Seafood harvesting
Rockfish, flatfish, sea cucumber and more — in legal zones, through a dive center.
Two uninhabited islands
Regions by departure port
Boat diving to offshore uninhabited islands such as Gyeokryeolbiyeoldo. Departs from Anheung Port (Geunheung-myeon).
Offshore archipelagos such as Sibidongpado, Heukdo and Jikdo. Departs Gunsan Port, Bieungdo, Yamido and Maryang Port.
Offshore islands such as Oeyeondo (departs Daecheon Port). Diving details unconfirmed — pending further research.
Baengnyeongdo, Deokjeokdo, Guleopdo and more (ferry from Incheon Port). Diving details unconfirmed — pending further research.
Offshore waters reached by charter boat
Reach Taean, Boryeong or Gunsan via the West Coast Expressway, then board a boat.
Offshore sites have no scheduled ferry, so trips run by charter boat.
Arrive at Incheon (ICN) and travel overland. English-speaking centers unconfirmed — arranging an interpreter is recommended.
A region without local specialist centers
Specialist centers based locally are rare, and it is common for clubs from the capital area and inland to run charter-boat trips. To avoid friction with fishermen and the coast guard, legal diving through a resort or center is recommended.
※ Cross-links to sites served by centers in other regions (dive_sites_served) are planned.
- Quantitative water-temperature and visibility values are unconfirmed (null). Diving details for Boryeong (Oeyeondo) and Ongjin, Incheon (Baengnyeongdo, Guleopdo, Deokjeokdo) are pending further research.
- Current coordinates are based on the two collected sites (Gyeokryeolbiyeoldo, Sibidongpado) — a coverage range, not the entire region.
For expedition divers
who read the tides
Dive into the West Sea.