Simply follow route 10 until you reach a Pokemon center with a bunch of cuttable trees near it. It's east of Cerulean city if you look at your map.
The entrance to the cave is to the left of the Pokemon center.
rock tunnel
Rock Tunnel is located due east of Cerulean City, around the corner from the pokecenter.
You take rock tunnel..........
Rock Slide is taught by a move tutor in Rock Tunnel.
On the way to rock tunnel,near cerullean city
Go east from cerulean city keep going until you reach water go south and into the cave this is Rock Tunnel.
in power plant, near entrance to rock tunnel, have to surf to it
use the move Flash (TM70)
After getting HM1 CUT go east of cerulean city and cut down the tree, continue east and eventually find a cave that is rock tunnel.
head west of cerulean city to the Rock Tunnel
i caught mine on the path from Cerulean city to Rock Tunnel
you can find zapdos in the power plant just below the rock tunnel