With Silph Co. liberated, Saffron City is now fully open. You can challenge Sabrina, the Psychic-type Gym Leader. After obtaining the Marsh Badge, your next destination is Cinnabar Island. To get there, you'll need HM03 (Surf). Head south from Pallet Town onto Route 21, or west from Fuchsia City onto Route 19 and 20. Both paths involve surfing across the sea to reach Cinnabar Island, home of Blaine's Fire-type Gym.
