EMERYVILLE (CBS SF) — A craft that was initially reported as a downed airplane in the water near Emeryville Sunday afternoon turned out to be an unoccupied homemade submarine, according to authorities.

Officials with the Alameda County Fire Department said they received the report of the downed aircraft at 12:39 p.m. in the water near Powell Street and Anchor Drive.

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Two rescue boats with the fire department investigated the scene and found that the supposed aircraft was actually an unoccupied homemade vessel similar to a sub.

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One of the fire department rescue boats towed the vessel to the Emeryville Marina. The vessel was registered and tagged by the Emeryville Police Department. 

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Berkeleyside reported on its Facebook page in March the vessel belongs to a UC Santa Cruz PhD candidate.