There's a secret room in the Ocean View Apartment, Ocean View Hotel. The purpose of this room is unknown. The room is adjacent to the artifacts in the aquarium, speculated to be a part of The Hidden Treasure Theory.
Many were unsure about the existence of the room until a thread on Neoseeker, discussing the conceivable purpose of the room in the game. Later on, attempts were to look through the door. It was initially considered that the door could be opened after 100% completion, but later on, it was proven to be false and the door served no purpose in the game. It was also theorized that it could be a portal to Marco's Bistro's interior inside the hotel.
In 2017, a user discovered a bizarre texture glitch regarding the room's door in the mobile version of GTA Vice City. The texture was replaced by a crack texture, with the rest being transparent. There were rumors that the door is non-solid, and that it is an entrance to the Ghost World, but they were quickly proven to be false. It is assumed that the texture is an invisible wall.