Refers to the location where someone (often a fugitive or person in hiding) is staying concealed. Commonly used in news reports about criminals or missing persons.
警察は犯人の潜伏先を突き止めた。
The police tracked down the criminal's hideout.
彼の潜伏先はまだわかっていない。
His hiding place is still unknown.
Compound of 潜伏 (せんぷく, 'hiding, lying low') and 先 (さき, 'destination, place'). The reading さき is a standard kun'yomi for 先 when used as a suffix indicating a location.