A Dictionary of the Book of Mormon/Mocum
MOCUM. A sin stained city mentioned but once in the Book of Mormon (III Nephi 9:7), and then in connection with its destruction at the time of the crucifixion of the Savior. It sank into the earth, and waters came up in its place, that the wickedness and abominations of its inhabitants might be hidden from the sight of Heaven, and that the blood of the prophets and saints might not come up any more before the Lord against them. No clue is given to the region where Mocum was situated.