To get the Slime Key you will need to get into Kanalet Castle, and collect all the Golden Leaves. Once both these things are done (if you haven’t done them yet, just follow the linked guides), you will then need to go to Mabe Village and get yourself a Shovel. You can buy this item from the shop for 200 Rupees.
How To Get The Slime Key
When you have the Shovel, return to Richard’s house and speak with him. He will thank you for getting his Golden Leaves, and instruct you to push a statue. Doing so will open a passage underground.
Head down and be careful, green blob enemies will come up from the ground. Push the stone out of the way and jump the hole to get at the chest. Then go the other route and take the stairs up.
This will bring you out in the field outside Richard’s house. What you want to do is cut your way through the bushes, but be very carefully. Many of them hide potholes, so don’t fall in. Slowly make your way south, the south east, the northeast, then northwest. You are trying to make your way to the statue in the top left corner of the field.
Once you reach the statue, dig at the foot of it to find the Slime Key. From here you can jump across a hold to the left, then use the key.
You won’t be able to enter the dungeon just yet. Head south, all around Richard’s house and field, until you come to a gap you walk through. Head south to the small islands, then jump between them to reach the door of the dungeon.
