The Rock Tunnel Connects Route 10 to Lavender Town. To get through, you need to have a Pokémon that knows the HM05 Flash. There is also a Move Teacher who will offer to teach Rock Slide to one of your Pokémon on the second floor.
If you picked Squirtle or Bulbasaur as your starter and leveled it up decently, you'll have little problem getting through. Those who picked Charmander as their starter will struggle though, as the rock types here are super effective against fire types. Pick up as many super potions as you can in Vermillion City, as you'll be using them. Worry about getting to the other side and come back for the items/Pokemon later once you have a stronger team.
On the second level, in southwest corner, there is a guy who will teach your Pokémon Rock Slide.
Items
- Max Ether (North of Picnicker Sofia and Hiker Dudley)
- Revive (B1F; southwest corner)
- Escape Rope (Southeast of Hiker Lucas)
- Pearl (North of Picnicker Dana)
- Repel (1F; northeast corner)
Pokémon Found
| FireRed | Level | Encounter Rate | LeafGreen | Level | Encounter Rate |
|---|---|---|---|---|---|
 Zubat
|
15-16 | 30% | Zubat
|
15-16 | 30% |
 Mankey
|
16-17 | 15% | Mankey
|
16-17 | 15% |
 Machop
|
16-17 | 15% | Machop
|
16-17 | 15% |
 Geodude
|
15-17 | 35% | Geodude
|
15-17 | 35% |
 Onix
|
13-17 | 5% | Onix
|
13-17 | 5% |
Battles (In Cave)
| Name | 1st | 2nd | 3rd | 4th | Money | |
|---|---|---|---|---|---|---|
| 1 |  Ashton
|
 Cubone 23
|
 Slowpoke 23
|
 1104
| ||
| 2 | Winston
|
Slowpoke 25
|
1200
| |||
| 3 |  Martha
|
 Oddish 22
|
 Bulbasaur 22
|
440
| ||
| 4 | Steve
|
 Charmander 22
|
Cubone 22
|
1056
| ||
| 5 |  Allen
|
Geodude 25
|
900
| |||
| 6 | Eric
|
Machop 20
|
Onix 20
|
720
| ||
| 7 | Lenny
|
Geodude 19
|
Machop 19
|
Geodude 19
|
Geodude 19
|
684
|
| 8 | Oliver
|
Onix 20
|
Onix 20
|
Geodude 20
|
720
| |
| 9 | Lucas
|
Geodude 21
|
 Graveler 21
|
756
| ||
| 10 | Sofia
|
 Jigglypuff 21
|
 Meowth 21
|
 Pidgey 21
|
420
| |
| 11 | Dudley
|
Geodude 21
|
Geodude 21
|
Graveler 21
|
756
| |
| 12 | Cooper
|
Slowpoke 20
|
Slowpoke 20
|
Slowpoke 20
|
960
| |
| 13 | Leah
|
 Bellsprout 22
|
 Clefairy 22
|
440
| ||
| 14 | Ariana
|
Pidgey 19
|
 Rattata 19
|
Rattata 19
|
Bellsprout 19
|
380
|
| 15 | Dana
|
Meowth 20
|
Oddish 20
|
Pidgey 20
|
400
|
Battles (Outside Cave)
! style="background-color:#c080ff;color:#ffffff;" |
! style="background-color:#c080ff;color:#ffffff;" | Name
! style="background-color:#c080ff;color:#ffffff;" | 1st
! style="background-color:#c080ff;color:#ffffff;" | 2nd
! style="background-color:#c080ff;color:#ffffff;" | 3rd
! style="background-color:#c080ff;color:#ffffff;" | 4th
! style="background-color:#c080ff;color:#ffffff;" | Money
|- align="center"
|16
|Carol
|Pidgey 21
|
Pidgeotto 21
|
|
|420
|- align="center"
|17
|Clark
|Geodude 21
|Onix 21
|
|
|756
|- align="center"
|18
|Trent
|Onix 19
|Graveler 19
|
|
|684
|- align="center"
|19
|Herman
|Cubone 20
|Slowpoke 20
|
|
|960
|}