To quote lead author Dr Vincent Post of the National Centre for Groundwater Research and Training (NCGRT) and the School of the Environment at Flinders University, "The volume of this water resource is a hundred times greater than the amount we've extracted from the Earth's sub-surface in the past century since 1900."
There are two ways to come to the precious water beneath the sea, one is to build a platform at sea and drill directly into the seabed, or to drill on the mainland or islands close to the aquifers - underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well.
However, Dr Post also warns, that there under ocean water containers are non-renewable, "We should use them carefully -- once gone, they won't be replenished until the sea level drops again, which is not likely to happen for a very long time."