In Gangnam: Olive Young Central Gangnam Town (403 Gangnam-daero, B1–4F), 10am–10:30pm, and Gangnam Woosung Store (320 Gangnam-daero, 1F), 9am–10:30pm, handy before a morning meeting or flight. Madeca Hydra Calming cream (50ml + 15ml) has 326 reviews; 50ml is fine for carry-on.