In Haeundae, try Olive Young Haeundae Station (7-5 Gunam-ro 8beon-gil) near
Haeundae Station and Haeundae Jungang (27 Gunam-ro) on Gunam-ro, the street to the beach. Easy to stop by on the way to the sea. Mamonde Liquid Mask (21K+ reviews) is 80ml, within the carry-on liquid rule (containers up to 100ml). Recs: 2