This achievement is unlocked by completing the Moon Grotto area, which is pretty early in the game.
When you approach Gumo he will pull a lever and you will fall through a trap door into the area and land on a Map stone, Be sure to pickk up the nearby map fragment and place it into the stone. You know you are going in the right direction as there are many short cutscenes of Gumo, just keep following him. Head through the level and eventually you will pick up the Double Jump ability.
Eventually you will reach an area where gumo pulls a lever and boulders keep falling, use your double jumpto climb this shaft avoiding the boulders and approach gumo. He will leave you the Water Veinwhich grants the entrance t the Ginso Tree.
If you are struggling click on the walkthrough tab and there is an excellent achievement /guide attached to this game