SPOILER
The trick is that you can circle around some vines sticking yourself to the walls and going behind rocks. Walls has 1 tile of room for the player to move, and you can go behind tall rocks. The minimum vines you can cut is 6 including the 2 at the begining which Nii comments.
If you've been doing this and the chest is still broken, there must be a bug, let me know if that solves the issue. I'll double check it anyways.
Alternatively I can tell you the exact route if you like.
I have rchecked It can take up to 7 hits, so 8 hist to get destroyed. But this not enough. And for the wall, what wall I am a solarus veteran, in Solarus games they are a lot of muzzle that can be solved.
And in DX the last level sword is hidden withina secret minidungeon hidden in a other dungeon and to access it you need to hugs walls.
So it was one of my very first reflexes. Asuming there must a be a secret shortrcut.
Either I don't live to my reputation, you didn't implemented it correctly, or you meant something else and then I have to destroy more vines that the chest have hits.
P.S spoiler.
At the very end you meant..... There is not tall rock here. Because the tile behind teh tall rock at the bottom doesn't lead anywhere.
