Bermeja Island was a phantom landmass documented in Gulf of Mexico maps from the 16th to early 20th centuries, positioned northwest of the Yucatán Peninsula. Its alleged disappearance sparked theories ranging from cartographic errors to deliberate destruction for oil rights.

Despite Mexican government searches in 2009, no physical evidence was found. The mystery intersects with geopolitics, as Bermeja's existence could have expanded Mexico's maritime claims over oil-rich waters.

While some attribute its absence to natural erosion, conspiracy theories suggest human intervention. The debate endures, blending history, science, and intrigue over whether Bermeja was real, mistaken, or erased.