First off, playing on switch. I was in the mines and got to the chest on floor 50. It was getting late, so I opened the chest then I quickly grabbed the item and left. When I started my next day, I found my watering can missing. My thinking is that I somehow left my watering can in the floor 50 chest. I haven't received any of the usual methods for retrieving lost tools, so I believe the game thinks my watering can is stored in the dungeon chest. However the chest is now gone, so I have no feasible way to access it.