It is my second watch from Tarkovsky the first being "The Stalker". The film is dark,contemplative and transcendental. It has the capacity to take you off into the realm of the often ignored part of the consciousness:chaos. It's far beyond Kubrick's Space Odyssey as it very devotedly emphasizes the human psychological structures.
The space where the Ocean is, is a sort of a bridge between the Earth and the Ocean(read the unknown). And why particularly the space ? Maybe because what we have within is that vast, endless and eternal space where there are infinite possibilities, where there is no barrier of time and closures. The space gives the humans the opportunities of confronting their darkest desires and wishes, somewhat similar to what the Room in the Zone(The Stalker) offers. The film throughout portrays the struggle within the human mind between the known and the unknown, peaceful liaisons and shocking realizations...between time and timelessness, space and void.
In the ultimate scene the audience is offered with an eerie suggestion, a brutal alternative... a sanguine complication: life on the impossible and invisible surrounded by a ghastly vortex of the untrodden.