Pokémon Red and Blue/Route 21

'''What was once fantasy is now amazing reality. Scientists on Cinnabar Island confirm that they can, indeed, clone Pokémon from fossils! To reach Cinnabar Island, Fly to Pallet Town and Surf to the south. You'll contend with plenty of waterborne trainers along the way, so be sure to replenish your Pokémon for the journey. Once you make it back onto dry land, you'll be on Cinnabar Island, home to the mysterious Pokémon Mansion.'''



So many choices!
There are only two other Gym Leaders to defeat: Blaine in Cinnabar, and Giovanni back in Viridian City. But your new Surf skill has opened up a couple of other new options. You can head back to Route #9 (past Cerulean City) and get yourself a powerful in the optional Power Plant dungeon, or head south from Fuchsia to get an  in Seafoam Island.

However, this walkthrough recommends that you head to Cinnabar Island first, to defeat Blair and turn your fossils into Pokémon that may aid you on your other quests. Still, the choice is yours, and you can go straight to the Power Plant or Seafoam Island, and return to this page when you're ready.

Cinnabar Island is just south of Pallet Town, so Fly back there and jump in the little pond to Route #21. Blue and Red players who couldn't get a in the Safari Zone can pick one up in the grassy area directly south of Pallet Town.