The three trees out front by the whirlpool with the shell charm? I've tried there a bunch of times and found nothing.

Edit: I'm an idiot. I was overthinking this and using my shovel.

No, I just need to interact.

It is right in front of my character.  It also says this is the mine-shaft on that sign to the right.

As to the treasure locations, I have no clue.

I've looked all over, I can't find the location of the treasure in-between 3 trees. Help?

In the top left of the cellar there is new instructions. To reset the levers, flip the grey one.

___________________________________________
############################################################################################
FATAL ERROR in
action number 1
of Other Event: User Defined 5
for object obj_dungeoncontroller:

Push :: Execution Error - Variable Index [0,6] out of range [1,6] - -7._dungeonMonsterSpecies(100003,6)
at gml_Script_dungeon_respawn_monster
############################################################################################
--------------------------------------------------------------------------------------------
stack frame is
gml_Script_dungeon_respawn_monster (line -1)
gml_Object_obj_dungeoncontroller_Other_15
called from - gml_Object_obj_dungeoncontroller_Other_11 (line -1) - <unknown source line>
called from - gml_Object_obj_dungeoncontroller_Step_0 (line -1) - <unknown source line>

This just happened randomly in the temple. No idea why. I'm going to use the monster repellent till the problem in temple is fixed.