I found it quite easy so ill tell you how to do it.
First you open the door to get into the cave
then you fill it with water
then you dive in and drain the water
then click in the area where the chest used to be
click on the ledge you are standing on to make a monster come
click it again and you will get to level 2
Btw i have finished both the smart stick adventures so ask if you need help again
