Pokémon Red and Blue/Route 9-10

'Using the Cut ability, chop your way through to Route #9 from Cerulean City. Check into the Pokémon Center near the entrance to the Rock Tunnel, then plunge into the underground passage. It emerges on Route #10, a very short route to your next destination, Lavender Town. This might seem like a roundabout way to get there--but it's the only way.'



Before the tunnel
The encounters here are annoying, but at least many of them can be avoided and there's a Poké Center at the end. Make sure you have your Cut-knowing Pokémon with you, or the HM and a Pokémon who's willing to learn.

Before you enter the tunnel, hack aside the top bush and search beneath it for a Super Potion.