It's difficult for me to figure out where is the right block? I pick up the key in the last block. However, the next block is alrady crashed. I don't know to jump to which right block? I often fall to the water. Should I jump behind the wall which is broken?

Please, give me your hint!!

After you obtained the key you have to make your way back to where you entered the room.
Above the entryway is a ledge you have to jump to. Use it to get to the righthand side of the room (righthand: means facing the entrance).

Jump to the next block, drop down to the block below, then jump over the blocks near the water back to the side where you found the key, but on the lower blocks. Inbetween you will have to use the whip to get along.

Then make your way yet again to the righthand side and climb up. From there on you should have no problems.

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Snakes ! I hate snakes !