Beneath Gardenia (ガーデンガーデン 下水道, Gādengāden Gesuidō?) is a location in Final Fantasy Dimensions. Like its name, it's located under Gardenia. It's a secret passage that links Gardenia and Desert Moon Hideout, which is located under Gardenia Slums.
After receiving a warning from a badly injured member of the Desert Moon in the Forest Hut, the Warriors of Darkness and Matoya go to her room in Gardenia and open a secret door, which leads to this area. They then use this secret passage to get to Desert Moon Hideout.