The Fortress Store Room Key is hidden somewhere in an active Sea Fort. To get the key, you’ll have to rummage through every nook and cranny of the Sea Fort to find its hiding place!
Where is the Fortress Store Room Key?
The Fortress Store Room Key is hidden somewhere in an active Sea Fort. However, while the Fortress Store Room Key is guaranteed to be at an active Sea Fort, the key will not spawn at an inactive Sea Fort.
You can specifically find a Fortress Store Room Key inside any of the many objects you can interact with at the fort. This includes the cabinets, cupboards, or crates. It can spawn on any floor of the Sea Fort as well.

Don’t forget to check outside! It is also possible to find the key in one of the wooden crates there.
As you search the Sea Fort, you will find Gold Pouches, pieces of treasure, and eventually a Fortress Store Room Key.
Once you have the Fortress Store Room Key in hand, head to the top of the Sea Fort and use it on the door to open the locked room.

More about Sea Forts!
If you want to know more about Sea Forts, check out our guide on them here. We go over the difference between active and inactive Sea Forts, how long a Sea Fort reset timer is, and much more!