The surf shop was difficult to find, even with the address. Another surfer taking the class helped me find the location. There is not a clear sign, but you can look for the colorful fish-painted water tanks. I attached a picture. The surf shop is in the black brick building. If you want to rent a wetsuit it is 10,000 won and you need to ask.
Our instructors were friendly, and an awesome perk is that the surf shop takes pictures and uploads them at the end of the day on Naver. You get to take some pictures before you go in the water, and also when you catch some waves. The water is quite shallow, so you can stand while you wait for your turn to surf. Thanks for the great day!