Estimates of the amount of water in the mantle range from ​1⁄4 to 4 times the water in the ocean.[10] There are 1.37×1018 m3 of water in the seas, therefore, this would suggest that there is between 3.4×1017 and 5.5×1018 m3 of water in the mantle. Constraints on water in the mantle come from mantle mineralogy, samples of rock from the mantle, and geophysical probes.