How can I get Hidden Keys?
You can earn Hidden Keys by completing orders from the Merchant Ship.

What can I use Hidden Keys for?

Hidden Keys can be used to open chests in the water at your Home Station, where you can receive valuable rewards. They can also be used to unlock Secret Chambers with energy boxes in event locations.

Where can I check how many Hidden Keys I have?
You can see your current number of Hidden Keys in your Storage, or by tapping on any Hidden Chest in the water.