I often hear of sharks appearing on the south and west coasts in the summer and making their way north through the summer but never heard of any in Gangwon Province.
The El Camino Packer has found a Korea Times article telling us exactly that. Click either link to see the 4 metre shark caught near Donghae. At 1.5 tonnes, I wouldn't want it around while I swam.
The El Camino Packer loves surfing and likely wears a dark wetsuit; the combined silhouette resembles a seal and is the staple food for great whites. He should be especially careful.
I may obey the lifeguards and stay within the buoy-line this year, especially if the buoy-line includes a shark net!