Roughly 85% percent of the mass of the universe is made up of material that scientists cannot observe directly. This material is known as Dark Matter, the bizarre ingredient that doesn't emit light or energy.
As per Space.com's Charles Q. Choi, 15% of the matter that isn't Dark - the matter we can see, the matter we can manipulate, the matter that comprises us - are just bubbles in an incomprehensibly vast sea of invisible low energy particles.
Experimental Proof of Dark Matter Ocean
Atacama Large Millimeter interferometer of radio telescopes situated in the Atacama desert of northern Chile has recently found massive galaxies amid on the ocean of Dark Matter. This interferometer actually founded that Massive Primordial Galaxies are Swimming in Vast Ocean of Dark Matter.
This clearly indicates that the Universe consists of a vast Dark Matter ocean and galaxies float over it. Hence, at the bottom of the universe, a vast ocean of Dark Matter exists.
Existence of SheshNag and Anant-Shesha
Theory of Dark Matter ocean may be new for the west but in our ancient Vedic cosmology it has been explained many years ago. This Dark Matter ocean is nothing but Garbhodaka Ocean on which cosmic Vishnu rests over SheshNag.
Desides this, Shesha is said to hold all the parallel Universes on his hoods and constantly sings the glories of the God Vishnu from all his mouths. He is sometimes referred to as Ananta Shesha which translates as endless-Shesha or Adishasha "first Shesha".
It is said that when Adishesha uncoils, time passes forward and creation takes place; when he coils back, a particular universe ceases to exit.
The theory of vast ocean of Dark Matter at the bottom of Universe is not a new theory, although space agencies now claiming it under their achievement.
How do Planets co-exist in Universe
Since the beginning of creation, the demons and the demigods, or the Vaisnavas, are always the two classes of living beings to dominate the planets of the universe. Lord Brahma is the first demigod, and Hiranyaksa is the first demon in the universe.
Only under certain conditions do the planets float as weightless balls in the air, and as soon as these conditions are disturbed, the planets may fall down in the Garbhodaka Ocean (Dark matter ocean), which covers half of the universe. The other half is the spherical dome within which the innumerable planetary system exists.
The floating of the planets in the weightless air is due to the inner constitution of the globes, and the modernized drilling of the earth to exploit oil from within is a sort of disturbance by the modern demons and can result in a greatly harmful reaction to the floating condition of the Earth.
How Hiranyaksa sunk the earth in Dark Matter Ocean
A similar disturbance was created formerly by the Demons headed by Hiranyaksa (the great explorer of Gold rush), and the earth was detached from its weightless condition and fell into the Garbhodaka ocean.
The lord as a maintainer of the whole creation of the material world, therefore, assumed the gigantic form of a Bour with a proportionate sout and picked up the earth from the water (dark matter / salila) of Garbhodaka ocean. This explanation is a slap on anti-hindus who make fun of Vraha Avatar story by saying that if Earth was sunk in an ocean then how the living beings living on earth were able to breathe.
GARBHODAKA ocean doesn't contain normal water but contains Salila and Dark matter, the main ingredients for the creation of Universe.
This should be now clear that there is a vast cosmic ocean of dark matter at the bottom of each parallel universe which is known as the GARBHODAKA ocean in our vedic cosmology.