The Anunnaki and the Abyss
When a distinguished but elderly
scientist states that something is possible, he is almost certainly right.
When he states that something is impossible, he is very probably wrong.
....Typically referred to as Hell, the domain of the Fallen Angels is an enigmatic place. Biblically and historically, Hell is said to be many things, including: a firey place of torment, a burial heap outside the city limits, the grave, the Bottomless Pit, the Abyss, and the Underworld. Several concepts have been melded together to form that one infamous and enigmatic residence of the Fallen Angels. When taken together, they describe various aspects of "Hell," which I think is the best possible answer to the question of what Hell actually is: rather than a single four word description, we can combine its many aspects for a clearer picture.
....For example, if Hell were literally the grave, how could it also be a place of torment or the Bottomless Pit? If it were literally a burial heap outside the city limits, how could it also be the underworld or a firey place of torment? Now combine the concepts: It's obviously connected to the "underground", thusly the grave, Bottomless Pit and Abyss references, which amazingly, also confirms it as the sumerian Abzu, the greek Hades and the Roman Pluto (not to be confused with the planet Pluto)! In other words, these concepts validate and as a whole, describe, at least one of the major domains of the Fallen Angels mentioned repeatedly, in nearly every culture in history. I say "one of the major domains," because, like it or not, the Fallen Angels have also set up housekeeping on Earth and around Earth space, as well.
....In fact, it is my contention that the Fallen Angels are more than partially responsible for most UFO activity and "alien" abductions encountered by humans down through the annals of history. Let's take, for example, the Anunnaki "Igigi" of Akkadian and Babylonian fame. The cuneiform word "gi"  is the symbol for sexual intercourse, to deflower sexually. "I.gi" means in Akkadian, inu "eye", and is combined with the symbol for deflowering sexually. "Igigi" can then be translated to mean, the "Watchers", the "Eyes in the Sky" who deflower sexually (et.al, the Anunnaki/Fallen Angels). Yet, according to the sumerian texts, the Igigi were the Greater gods and didn't come to the earth, but remained up in the sky, circumnavigating the globe. So how is it they "Deflowered" anyone while being uninvolved in the activities of the humans on the planet? Abduction, my friends, abduction. And they are still at it today. It says in the Bible that the Apocalypse would feature aspects quite similar to the days of Noah leading up to the flood, such as a huge population of nephilim created by Anunnaki involvement with our species, abuse of the environment, genetic manipulation of life on the planet, poisoning of our food sources, and so on, mostly as a result of their nephilim progeny carrying out the Anunnaki agenda. Here we go again. How ironic that even in the face of historical precedence, we are right back where we started from. Who is really in control of this planet? I'll give you three guesses and the first two don't count.
....Sadly, many from the UFO community do not recognize the danger of the Anunnaki. Afterall, they say, "didn't the extra-terrestrials save us from launching nuclear bombs at one another?" "Aren't they more advanced on the evolutionary scale?" This, they believe, is evidence that the aliens/Anunnaki/Fallen Angels, have our best interests at heart. However, many don't take into consideration the past of the Anunnaki and that their final agenda has not yet been met: that is, the annihilation of humans as an eternal LIFEform. As a human, if you die, your body can still be resurrected to eternal life. As a result, any actions they may or may not take, whether seemingly good or bad, will inevitably lead to the latter for as many people as possible. That's the plan, and it is clearly outlined in scripture with hundreds of other ancient texts from various cultures to verify the historical precedence. Don't believe me? Think I'm just a crazy Bible thumper? Read the Hindu Mahabarata. 
Let me reiterate: THEY ARE NOT OUR FRIENDS.
....Anyway, back to the topic of that enigmatic domain of the Fallen Angels. Some believe the Anunnaki came from Nibru and believe Nibru is another planet, elsewhere in the solar system. However, Nibru is spoken of in the sumerian texts as the holy city of Enlil, containing his temple the E-Kur, which sits on a mountain surrounded by cedar trees with a gate up to the heavens:
"In the city, the holy settlement of Enlil, in Nibru, the beloved shrine of father Great Mountain, he has made the dais of abundance, the E-kur, the shining temple [...]" "Enlil , when you marked out the holy settlements, you also built Nibru, your own city."-Quotations from "Enlil in the E.KUR" According to sumerian texts, Enki travels to Nibru, Enlil's city, where he meets with the other Anunnaki, including Enlil and they proceed to get totally drunk. No gates, no fanfare, no heaven-earth bond, he just travels to Nibru. This Nibru, my friends, is/was not another planet. It was right here on good ole' Terra (Earth) at Enlil's city. However, the Abzu does lead to some otherwordly place and that place is most likely not the literal center of the Earth or "underground." The only thing that is or was underground was the "door" to the star gate itself, called the Abzu which leads to Erkalla or Kurnugi (among other distant places in the universe), the land of no return (for humans, anyway), the land of darkness, pain, sorrow, and so forth, very "Abyss-ian" if you ask me! Conversely, Enlil, an Anunnaki and Enki's father or brother, depending on which story you read, appears to have had a star gate of his own at E.KUR in Nippur, called the DUR.ANKI, the heaven-earth bond, which lead to the Courtyard of "An" in "heaven", who was the premiere Anunnaki. Both of these "star gates" have seven gates between Earth and their final "mentioned" destinations.  The salient point to remember here is that they were all sons of Jehovah Elohiym (et.al, other creations) and not literally Elohiym, themselves (although I have seen them described as elohiym (diminutive)). As yet, I have no reason to believe that "An" was Elohiym either, but I have plenty of reason to believe Enlil and Enki were Angels created by Elohiym, in a different creation cycle before our time.
....The gods and the greater gods, were most likely the fallen angels and the fallen archangels in many cases, and would correspond with the sumerian Anuna and the Anunnaki/Igigi. There's historical precedence for this viewpoint in the ancient Hebrew texts, the Bible and various other ancient texts. I believe these texts indicate that the fallen angelic beings were "stuck" as it were, in the physical universe and have to rely on technology in order to traverse the reaches of space, having been stripped of the ability to cross the dimensions into God's presence (They were "cast out of Heaven"). However, the holy angels and archangels have an entirely different set of abilities and options, from what I can ascertain. They are primarily messengers, and stay out of human affairs with the exception of when under direct commandment from God, which typically involves protecting humans from the fallen angels. In fact, many times in the Old Testament and New, you can read about the angels protecting humans from various problems almost always directly associated with the fallen angels in some aspect. The good news is, if you're an abductee or don't wish to become one, there is someone who can protect you from abduction by these extra-terrestrial, fallen angels. His name is Jesus. More on that later.
....So there you have it. The Fallen Angels, in most cases, are extra-terrestrials, responsible for many (if not all) legitimate accounts of abductions and sightings. They have employed technology to mimic the works of God down through the millenia. By manipulating the physical realm with dramatic outcomes, they have convinced many that the spiritual does not exist and that all instances of the miraculous are/were simply clever aliens using technology or explainable by the sciences, as they have done for thousands of years. They've implanted their hybrids in the highest offices of our lands and in the seats of power of every major institution and corporation, for as long as there have been seats of power to sit upon. If you've ever wondered why you couldn't get ahead in life, no matter how hard you tried, you have only to give thanks for your humanity (and do give thanks for it). The invisible ceiling we've all suspected existed in the higher eschelons of power, does indeed exist. We may no longer have to wear our place in the caste system boldly painted our foreheads today, but that doesn't mean we aren't still categorized for success or failure from the moment of birth. Any variation or deviation from the poverty and servitude normally assigned the lowly human race by the fallen angels and their prodigy, is truly a miracle of God. If you're successful, give thanks to God, repeatedly, because literally billions of humans down through the history of planet Earth have not been as fortunate.
....So what does all this have to do with the Abzu and the Abyss? That is the subject of the next chapter.
1 Lost Treasures from Iraq - Oriental Institute, University of Chicago
3 The Mahabarata - Internet Sacred Text Archive
4 Enlil in the E.KUR - Earth History
and Ereshkigal - Earth History