There are numerous ways of coining what some psychiatrists call an Oceanic Experience. You might hear terms like the Oceanic Feeling or a Peak experience, but all these are in fact the same thing, a Mystical experience, an intense feeling of Presence in the Now.
The most curious thing about these experiences is surely the fact that they often, if not always, come out of nowhere and quite unexpectedly. But that's only true for those who are not aware of what triggers them, or what sets these emotions into motion. Some would argue this is not even a specific emotion, but a State.
I want to tell you how you can try and find these triggers and stay Oceanic for as long as you can hold that concentration and Presence. Later you will not need to concentrate at all.
The key point I must first make is this: Everyone can have this experience. There's a somewhat short-minded idea floating around that says we are hard-wired for religion. That is not true, we are hard-wired to experience this sensation, western religion simply monopolized it and made most believe they need something to experience it, and instead of showing others how to do it, wrapped it up in ritual and community, which are very superficial aspects of it and may aid you in becoming Oceanic, yet you can do it by yourself. Which makes sense doesn't it, since you are the I to whom it happens, so the very notion that you need something else is a bit ridiculous. Don't worry if you are confused about what I'm talking about, because you most definitely have experienced Oceanic already, everyone has, although it is often the case that you don't realize this fact.
It is also important to note that the trigger will not be different for everyone, and that Peak experiences are triggering a state of Presence. Simply put, we all have the same triggers because we are all one I manifesting in countless expressions.
The beautiful thing about these experiences is that, once you know the trigger, you can stay in that feeling for as long as you wish under certain conditions.
The term Oceanic was coined by Romain Rolland and popularized by Sigmund Freud, who pointed out that this emotion may be a fragment of infantile consciousness, a feeling which occurs when the infant begins to differentiate himself from his human and non-human environment and a survival Ego begins to form. I tend to disagree with this notion. The disagreement stems from the fact that Oceanic doesn't come from differentiation, but from a sense of you and the thing that is 'outside' you (environment) being one and the same thing. If anything, differentiating yourself from everything else causes the feeling to stop, as you resume your default experience of consciousness; which is a feeling of centrality, of the I and Other. Or in a very strict sense, the sensation stops when you stop being and start thinking.
There is no Other in Oceanic, but rather a deep sense that all things are the same one thing, which is I.
Freud was right about the 'infantile consciousness' part however, as it is indeed a fragment of that consciousness. It is why it has a subtly deep sense, a sort of 'primordial' feel to it, meaning that you get a sense that this sensation comes from the very core of you. That's because it does. Yet Freud's explanations were never deep or remotely spiritual enough. And having been oceanic for 1-2 days on a few occasions and for up to an hour in meditation, I have come to realize his "everyone wants to return to the womb and uses sex to try and do that" is simply not adequate enough, as it dismisses a deeper layer, which is that our most basic need for intimacy is the result of an even deeper need that is produced by the centrality of I, and that sex is the most superficial step of achieving what is really sought after by most (usually subconsciously): a Merging. A merging of subject and object. Of subject and other subject, which for the I is the object as it seems to be outside the I. It is a need to return to the womb where the baby was completely submerged and weightless, fully in tune with its surroundings and in that sense, One with it. A merging of the male and female aspect in sex can cause that trigger, but also because it puts you intensely into the Now.
Images are important for you to enter this state if you are a beginner and don't yet know how to still the mind, especially if you belong to the 60% of people who prefer visual stimuli out of all other.
If you recall the sights, smells and sounds from the first time your were Oceanic (obviously not while you were in the womb), it will be easier to reach the state again, but such things are only of help. When it comes to smell, it is more likely that the precise fragrance will not be imprinted upon your mind, but the certain subtleties of it.
You must remember that you can reach this state even without these triggers. They are here simply to help you at first. And since in western society doing something purely to do it (like meditation) can be very useless for most, this trying to become Oceanic may be used as a goal for you to work towards while meditating. Mediation is at first a training in concentration, because until you learn concentration, or a better term would be perhaps contemplation, you will always try and control your mind instead of simply not paying attention to it. This method is a good way to learn, as you will find that your mind, once it reaches this state, may automatically try to cling to it, and in that clinging, lose the feeling. Try it and you will see the realizations you get from this.
Through my talks with those who had consciously had the experience and reading about detailed cases of it, I have come to a few conclusions of the aspects required in terms of outside happenings to reach Oceanic. Allow me to list them out and explain a bit more why they work.
1. The quality of light. (early morning gold usually works best as it slants low in the sky and has an increased scattered effect, meaning you feel more immersed and a part of it)
2. Random background sounds that are of a natural source, like a stream or the rustle of leaves or the song of birds. (you already know what these sounds are, so a mind that is used to compulsive thinking will not attempt to label the sounds but just let them be. This will again help in the sense of being immersed in the sounds, until you eventually no longer hear a bird chirping, but in a somewhat funny sense, become the bird.)
3. A sight of something which seems finite over a backdrop of something that appears infinite. For instance, the sight of pine trees against a blue sky. [I used pine because they posses a denser quality] (this aids greatly in the sense of merging of the object and the subject. Clouds and the sky are a good way to do this as well, as you might begin to realize a truth that may seem banal if someone tells it to you. It is that the clouds and the sky are not separate things, but that the cloud is the sky. In much the same way, this trigger helps with the realization that Self and Other are not separate, but that the illusion of separateness is created by the sense of centrality that is the individual consciousness.)
4. Smells of trees in bloom or wood in general. (in much the same way as sounds, these smells already have a label in your mind as to what they are and, as such, will not cause the compulsive thinker to try and identify them, but instead simply let them be)
5. A peaceful mind absent of concerns, even if only for the time being. (this is a plus, as meditating on specific things will be easier)
Posture will be important, but not absolutely necessary. Resume any of the comfortable meditating positions, although it is advisable to take on any of the zazen postures for best results, even if it can be very unconformable for you at first. But a bit of discomfort is good as it assures you will not fall asleep or get sleepy.
What these things will help you with is to realize the Now and that It is all there is, and that you are it. You might say, I already know there is nothing else but the present. Yes, of course you do, at least you believe you do as your mind does, but do you feel it? The distinction is more important than you might think.
And that is what Oceanic really is, an intense Presence in the moment, where the future and past dissolve, or rather, the illusion that these two states of time even exist, disappears.
Focusing on these triggers will help you stay in the Now, they are grounding you in the Now. Leave your mind alone in these moments and you will find the ocean and in the ocean, everything that is You.
The exercise might seem a contradiction to what mediation is, which is a way to calm the mind, but in reality, compulsive thinking and thinking while fully present in the now are not the same things, as you might have found out or already know.
And, as I said, once you can cultivate this feeling anytime you wish, you will no longer need any triggers, but will simply breathe in, breathe out, and be it.