Here is a quote from the article
A reservoir of water three times the volume of all the oceans hasThe source linked here is the same link below:
been discovered deep beneath the Earth’s surface. The finding could help
explain where Earth’s seas came from.
The water is hidden inside a blue rock that lies 700 kilometres
underground in the mantle, the layer of hot rock between Earth’s surface
and its core.
Some geologists think water arrived in comets as they struck planets,
but the new discovery supports an alternative idea that the ocean oozed
out of Earth’s interior layer.
Massive 'ocean' discovered towards Earth's core - environment - 12 June 2014 - New Scientist
Made me think about that this might answer the question about where is the rest of the water that covered the earth during Noah's flood.