30 blueberries. You need to collect that many and give them to the elite bear guard who stands in front of the Sun Well. You need to dip your goblet in to its water and drink from it. It's supposed t give you magic power. According to the old man, who told you about it, the power you receive is randomly generated, but all of the possibilities are useful powers like seeing in the dark, teleportation, healing, casting minions or flying and a lot of others. The bear told you he'd met 4 people so far who drank from the magic water and he's been working here since 12 years. Good luck!
Walkthrough for Delicious Forest Blueberries Escape