"If we could take all the water which is locked up in the moon's interior, it would make a one-meter-deep [one-yard-deep] ocean covering its entire surface," said lead study author Francis McCubbin, a geologist with the Carnegie Institution for Science in Washington D.C.

McCubbin's team reanalyzed old moon-rock samples gathered by Apollo missions and a lunar meteorite found in a desert in Africa. (Related: "Apollo 11 Hoax Photos: Moon-Landing Myths—Busted.")

The findings indicated that inside the moon "the amount of water is at least 64 parts per billion, which is two orders of magnitude more than previously thought," McCubbin said. "And maybe even more is there."

(Related: There's Water on the Moon, NASA Probes Confirm)

Using electron microscopes, McCubbin and his