How to get into the swamped room in the Heart of the forge? (Assassin's Creed: Odyssey)

On the volcanic island there is a place - the Heart of the forge. The door is locked by key, key give during the passage of an additional quest the Test of courage. The key I got opened the door and even found a helmet that need to find to complete the quest. But there are some littered the door where treasures are hidden. I searched - not found an alternative passage there. Location located to the room with the helmet, if you know what I mean. There is a suspicion that this location will open later in the new updates, adding new quest. At whom it turned out?