Ulleungdo Island

Dodong · Gyeongsangbuk-do · South Korea

Ulleungdo is a remote volcanic island rising dramatically from the East Sea, roughly 130 kilometres off South Korea's eastern coast. This rugged, sparsely populated island is surrounded by some of the clearest temperate waters in Korea, offering a diving experience that is raw, wild, and utterly different from the subtropical sites of Jeju. Its volcanic origins have carved a spectacular underwater landscape of caves, tunnels, pinnacles, and sheer walls that plunge into deep blue water. The diving around Ulleungdo is characterised by its volcanic geology. The island drops away steeply on all sides, with many shore-accessible sites reaching 30 metres within a short swim from the rocks. The most famous formations are the underwater caves near Elephant Rock (Gwaneumdo), where volcanic tunnels extend through the basalt, creating swim-throughs illuminated by shafts of filtered sunlight. These caves sit at depths of 13 to 15 metres, comfortably within recreational limits but dramatic enough to thrill experienced divers. Kelp forests are the defining feature of Ulleungdo's underwater landscape. Dense stands of brown kelp grow on every rocky surface, swaying rhythmically in the current and creating cathedral-like canopies that filter the light into golden beams. Schools of squid dart between the kelp fronds, sea urchins carpet the rocky substrate, and rockfish hover motionless in the green shade. The contrast between the dark volcanic rock, the golden-green kelp, and the deep blue open water creates an underwater aesthetic that is distinctly temperate and hauntingly beautiful. Visibility during the peak season of late July through September regularly exceeds 30 metres, rivalling tropical destinations. Water temperatures reach a comfortable 20 to 24 degrees Celsius during this window, making standard wetsuits sufficient. The island's isolation means marine life is abundant and relatively undisturbed, with dolphins occasionally spotted from the dive boat and diverse invertebrate communities thriving on the reef. Ulleungdo's remoteness is both its challenge and its reward: the ferry journey, potential weather delays, and limited infrastructure are the price of admission to one of Korea's most pristine underwater environments.