>>24872269Considering you can't have reached that point without Surf, I imagine you mean Waterfall, which is received from a female DH grunt in the DH hideout after you beat Turner.
Clearing the Ghost gym (the one you're stuck on) enables fly.
The path is not only invisible, but incomplete. Defeating the underling trainers restores the missing parts of the floor, and after you beat all of them you can reach the leader.
Walk up to the first trainer, get on her right side, then walk right until you're in line with the next trainer, walk up and around another in line to the left of them, walk left until you're in line with the leader, then walk up.
Course that's all off the top of my head and may not be 100% accurate but go nuts.
UNRELATED, these people talking about mew are making me feel retarded, because I've never encountered it on three playthroughs and only on this one have I even considered that it might exist since that girl in Porcelia makes mention of a certain pink pokemon. wat do.
