In Pastoria City, you'll find a Team Galactic Grunt blocking the entrance to the Great Marsh. After a brief encounter, he'll run off. Follow him to the Valor Lakefront. Here, you'll battle him again. After defeating him, Cynthia will appear and give you a SecretPotion to help the Psyduck on Route 210. Now, head back to Route 210 (the northern section) where the Psyduck were blocking the path. Use the SecretPotion on them, and they will disperse. Cynthia will then give you HM03 (Surf). You can now use Surf outside of battle, which opens up many new areas. Head east on Route 210 to reach Veilstone City.
