Ursula's Crystal Key unlocks the very first biome, the Mysterious Cave.
How to place Ursula's Crystal Key on Dazzle Beach – Disney Dreamlight Valley (with great power)
Unlocking content in Disney Dreamlight Valley requires reaching certain milestones across multiple character missions or unlocking specific game content.
this could be reaching a certain level of friendship for a character on a number of them, unlocking things, and even doing your mundane tasks like collecting drops, fishing, cooking, or pretty much anything in the game.
Ursula's Crystal Key is a quest that would be needed to unlock the mysterious cave. You must complete Merlin's Quest Friendship is Everything where you unlock the daily gift boosts as well as upgrade at least 3 characters to friendship level 5.
