Exploring the Mysterious Forest in Zelda: Link's Awakening comes after you've found the sword in Toronbo Shores at the start of the game.
This has you find the Tail Key location, which requires you get past the Raccoon by making use of the Toadstool.
If you're looking for more assistance, our Zelda: Link's Awakening walkthrough can help.
How to start exploring the Mysterious Forest
To get to the Mysterious Forest, head north-west out of Mabe Village, chopping down the bush then heading north to where the trees change colour.
After the conversation with the owl, head north to encounter a set of Moblins. As you explore the forest there will be more of them - some will carry a spear, or a sword and shield - in all cases, approach with your shield raised and let it attack.
It'll tire out after their attack - leaving them exposed and ready to be ripped into with your sword.
Just further north is a Raccoon, who after trying to go further north, will teleport you to the other side of the forest. Your task now is to get past that Raccoon - it says it is particularly sensitive to dust and powder, so let's get some items that might spook it away.
How to get the Toadstool and where to use it
After you try and move north past the Raccoon, you'll be teleported to the far east of the forest. You'll be next to a Great Fairy just above you, but ignore that and go left through the tight passage and down - or down, left and then up - to reach a log with a sign outside saying be wary of cracks in the floor. Head inside.
You'll be in a cave with purple crystals, Keese (otherwise known as bats!) and a chest. To open the chest, you must destroy all the crystals and work your way around to the right side of the room, moving quickly over the cracks in the floor.
Stay too long on them, and you'll fall. Round the other side, you can move the rock beneath the chest to the left by holding left, allowing you to open it and get 50 Rupees inside.
Head north, round the corner, and you'll appear in a room full of rocks and a Heart Piece. You won't be able to get this until you have a specific item to do so, so ignore it for now and head south out the cave.
You'll emerge at the far north-west of the forest.
Take down the Moblin, then to the left is a Toadstool. You can't do anything else here, so return through the cave and back to the far east of the forest again.
Now head north, and take a right at the log entrance surrounded by rocks. You'll now leave the forest and appear in the Koholint Prairie area. Go south here to find a witch's hut. Hand over the Toadstool, which will be mixed in the cauldron to make Magic Powder.
Our Zelda: Link's Awakening walkthrough and guide can help you with the critical path, including the Eagle's Tower and Turtle Rock dungeons. There's plenty to be done on the side, too - including Zelda Link's Awakening Heart Pieces, Zelda Secret Seashells and the Zelda Link's Awakening trading sequence. Finally, there's also the new Zelda Chamber Dungeons feature to unlock and complete.
How to get past the Raccoon and get the Tail Key location
Return to the forest again, and to the Raccoon's location - head back to the log cave entrance, then go left, then up - and use the Magic Powder on the Raccoon. (You can do this by equipping it in your inventory and assigning it to either the Y or X button.)
The Raccoon will transform back into Tarin, leaving the path north clear. Head up and open the chest to get the Tail Key.
Though you can leave the forest through this passage here to the swamp, you cannot explore it properly just yet - so head south out of the Mysterious Forest and make your way to the Tail Cave.
To reach the Tail Cave, head south out of Mabe Village to Toronbo Shores. Instead of going south onto the beach proper, head east through the wooded section, which snakes back and forth and pits you against a number of Octorok.
At the end of this section is the entrance to the Tail Cave. Use the Tail Key you found in the Mysterious Forest and head inside.