Thornfelt Swamp

Head east and defeat the multiply slime. Wall jump up to a level with rotating spikes.

Push the stone past the rotating spikes, just enough to jump over it.

Go east to the Spirit Well to save and replenish.

Return to the stone and push it all the way to the left, so it's slightly inside the thorn plants.

Jump on the stone, then wall jump up. Defeat the slime and continue wall jumping upwards.

At the top, head east to trigger a cutscene with the Gumon, who possesses the Water Vein. Note this location as the Ginso Tree is here; you'll return after retrieving the Water Vein.

Head east again, defeating the multiply slime. The Gumon will jump down; follow by dropping down the mid-levels first to collect energy crystals and life plants.

When you reach the bottom, you'll encounter ground slimes that pop up and shoot. Avoid killing them for now.

Go west and stand on the broken ground. Wait for a ground slime to fire a projectile, then move. The projectile will destroy the ground, allowing access to a Spirit Container below.

Head back up and go west. The Gumon will pass through a passage and lower a wall. You cannot destroy this wall with Spirit Flame.

Run past the ground slimes and jump onto the platform with the glowing stone. Wait for a ground slime to fire a projectile, then move. The projectile will break the rock, revealing another ground slime hole.

Continue west and jump on the next glowing platform. Position yourself so a ground slime fires a projectile onto it, revealing another ground slime hole.

Go to the purple wall erected by the Gumon. Wait near it and move when a ground slime fires at you. The projectile will break the wall, allowing passage.

Go west to reach Moon Grotto.