Check swell maps when there's a typhoon nearby. You need either a massive one from the south of Japan and Korea or one of any size to make its way into the East Sea (Sea of Japan). Ideally the typhoon or low pressure should be in the Northern corner of the East Sea.
Overview
Atmosphere
This place is empty. Koreans will think you're crazy if you go swimming on a flat day so you can imagine their reaction when they see you paddle out on a solid storm swell.
General
Rarely works but it's easy enough to monitor the weather and be there when it is going off. Maybe 20 times a year.
