Waterfall

Inside the waterfall is a secret cave with a staircase that leads to a sealed vault door. However, after activating all the hidden Beacons the vault door will open revealing a cave bar and a pool table. The bartender will sell you fruit punch while jazz music plays in the background. Above the bartender's bar, there are signs reading out "100% REAL FRUIT PUNCH", "BEST PLACE IN TOWN", "FUN PLACE TO CHILL AND CHAT", and finally "BUT IS THERE MORE?" Behind the counter is a pin pad connected to a door requiring 10 digits to be punched in. It is assumed that getting past this door gets you the badge "The Mystery" as so few people have unlocked it and the badge's description says "I have no clue how you managed to actually do this."

Update: The code is 21514519. Although it does not have 10 digits, entering it will result in the door being open.