The Earth has 17 different species, who are visiting Earth during the Transformation, living either within or under the seas. These alien species are not living in 3rd Density - spiritually or physically. They occupy the sea floor or the waters in 4th Density, so essentially, as far as humans are concerned, they do not exist. Why the seas? Because the depth of the sea floor places them closest to the center of a formulated center of the Earth, in 4th Density. We say formulated, as the Earth today is not in 4th Density, and thus these species are essentially floating in space, connected to each other in a sort of mesh or web. Why not simply occupy what would be the center of the Earth, or create a 4th Density space station, or perch on the Moon? Where 3rd and 4th Density substances do not interact, attempting to live within the hot, heavy, molten core of the Earth would be, shall we say, a drag. It places a burden on the 4th Density substances, and results in something like a chronic headache.
Being in or under the seas makes for an easy transition to and from 3rd Density, during visitations or contact in the form of sightings. Coming in from outer space is more complicated, especially as your governments consider this an arrival and departure. In the seas, these alien species are simply having one long stay.