The Legend of Zelda: Link's Awakening: how to unlock
Keys and prerequisites for important dungeon entrances.
Open Tail Cave

Take the Sleepy Toadstool from the Mysterious Forest to the Witch for Magic Powder. Sprinkle powder on the forest’s raccoon to restore Tarin, then head north to the Tail Key chest. Put that key into the keyhole beside Tail Cave south of Mabe Village.
Enter Bottle Grotto

After completing Tail Cave, BowWow is kidnapped. Rescue him from Moblin Cave in Tal Tal Heights by defeating the Moblin Chief. Take BowWow into Goponga Swamp and let him eat the flowers around Bottle Grotto’s doorway. He waits outside while you explore the dungeon.
Open Key Cavern

Recover all five Golden Leaves from Kanalet Castle and return them to Richard at his villa. He opens the route to his back garden. Navigate its hazards, then use the Shovel at the owl statue to dig up the Slime Key. Use it at Key Cavern’s keyhole.
Open Angler’s Tunnel

Bring Marin to sing for the walrus blocking Yarna Desert. Defeat the desert’s Lanmola to obtain the Angler Key. Insert it into the keyhole below the Tal Tal Heights waterfall to stop the water; then approach the revealed dungeon entrance from the mountain path above.
Summaries written for this guide. Artwork and screenshots © Nintendo.

