The mountain where you should be going to is the Death Peak in 2300 AD, not Mt. Woe, which is a mountain in 12,000 BC. If you got Magus in your party, use him because his magic works very well against the enemies in the Death Peak. When you fight the Lavos Spawns, keep attacking the head, not the shell. Watch out for the wind since it can knock you away from your route very easily, which can get a bit annoying. When you make it to the top, I'd suggest putting either Marle or Lucca into your party for a special scene between her and Crono.