Some of the following will be graphic, but I hope not gratuitously so.
I will use the words “climax” and “orgasm” interchangeably, though some use them to describe what they consider distinct experiences. I have a preference for “climax” as somehow more ordinarily human and less scientific sounding.
   As throughout this website, these reflections are shaped in important ways by the focus on marital relations: sexual relations between a man and a woman committed to each other for life. It may also be shaped by focusing more on relations between a husband and wife who both believe that there are important differences between men and women.

   Sexual climax is, as the term suggests, the peak or high point of sexual intercourse. It is – or at least can be, and usually is – extremely powerful. But it is also a fact of life that there is considerable variability in the experience of orgasm, both in men and women. Sometimes it is overpowering, but occasionally it can be fairly weak.
   Some articles that survey a wide range of the scientific study of orgasm can be found

here  and here.

 Describing Climax
   One interesting fact about climax is the incredible variety of the ways people describe it. Apparently, it is so distinctive that comparisons fail. Some people say it is like a sneeze – which I find completely puzzling. My stab would be that it is like a suffusion of the body with intense pleasure (for some reason, it begins in my legs and moves up, though I haven’t heard other men say that), culminating in an explosion of pleasure in the mind that lasts for about 5-10 seconds, give or take, then tailing off.
   One small observation I will make deals with the question whether the physical feeling of climax is continuous or comes in “waves.” I make this observation, because for many years I would have said that the pleasure comes in waves, but I eventually changed my opinion. I think the original opinion was based on a confusion between the genuine feeling of waves – which come from the rhythmic contractions that both men and women experience, associated both with the urge to thrust and (in men) with the emission of semen in spurts – and the actual feeling of orgasm itself. But the feeling of waves is, I think, distinct from the feeling of orgasm, which is a feeling of continuous intense pleasure accompanying, but not the same as, the rhythmic contractions and thrusting.
   It is often said that men and women describe climax in the same way, that it is fundamentally the same experience. Without denying that there may be considerable similarities, I find this really implausible. The most obvious reason to doubt it is that there is at least one very fundamental difference: when men orgasm, they usually enter the resolution (post-orgasmic) state immediately, while women may plateau, and go on to another orgasm. [I put the “multi-orgasmic male" phenomenon to the side, because it seems to be a relatively uncommon occurrence, and I have no direct knowledge of it.] Given the magnitude of that difference, it seems likely to me that there are also some differences in the actual experience of climax itself. But I also doubt whether this is a question that can ever be resolved, other than saying that the experience is at least similar. Feelings are, after all, intensely personal. I may know how it feels for me to eat a piece of great cake, but I am not at all sure I could describe it well to someone else.

Men, Women, and Male Envy
   If orgasm is extraordinarily intensely pleasurable (and it usually is), for men the intensity of the moment brings the paradox that it is almost always a complex of pleasure and disappointment, because its short duration (of 3, 5, 8 seconds) is a disappointment – because you want it to go on and on and on . . . and it doesn’t.
   This means that husbands unavoidably have moments when they really envy their wives, especially because of their capacity for multiple orgasms. And also because the moments before her orgasm (15, 20 seconds, or more) seem to have a pre-orgasmic intensity that a male's pre-orgasmic moments don't match - perhaps because he is in those moments the relatively “active” principle (active, because he is guiding the action, performing the actions that bring her pleasure – though also receptive because he is driven by the external stimulus of her desirability, responding to the demand he experiences of wanting to intensify her pleasure more and more and more).
   This envy is understandable, because (as I have pointed out elsewhere on this website) Teresias (of Greek myth – a man who became a woman for a time) was right – women do have greater physical pleasure in sex. But it is also wrong in important ways.
   It’s wrong, first, because wives, as much as they love the pleasure – even a very “ladylike” woman can say that at that moment she would do ANYTHING for it (sell out her country, kill anyone who got in the way – which, of course is not true, since she would respond to her needy child instantly, if necessary) – don't put as high a value on the pleasure itself as men do. The value of, the focus on, the personal union of husband and wife provides a context for the pleasure (in some sense, a “competing” value) that usually prevents her from focusing simply on her pleasure (as a man can do more easily); so, if men were women, they wouldn't be experiencing the pleasure in the same way they do as men.  (And, please, be careful not to misunderstand this argument – it’s nowhere near saying that women don’t experience physical pleasure intensely – especially as my next point suggests.)
   Second, a wife can experience a point during orgasm at which the pleasure becomes sooooo intense that it can’t be continued (if it did, it would be painful) – so that she may push her husband away and say "no more!" This is a profoundly puzzling moment for her husband, who has no idea what that can possibly mean. What is “too much sexual pleasure”?!  Bring it on! He is always dying for more.  If anything, he is always a little bit disappointed that the "more" (a continuation of his pleasure) is perpetually out of his grasp – it always ends before he has had “enough.”
   And yet that moment is, paradoxically, also an extraordinary high for the husband, because it immensely intensifies his sexual satisfaction (which is something broader than “sexual pleasure”).

   The moment of climax is also paradoxical in some ways. Think of the physiology of it. A husband typically arches his back, pulling him AWAY from his wife at this moment of greatest union – though, at the same time, with his thrusts he is reaching as deeply into her with his penis as he can (without hurting her), seeking her greatest depths. (Wanting to reach deep into her is one reason he’s arching his back.)
   And I think it is common for a husband to close his eyes as he climaxes, because the intensity of the moment may be diminished if he keeps them open, because seeing something, anything, detracts from the total focus on, total absorption in, the overpowering, intense pleasure of that moment – though, in the moments just before orgasm, the sight of his wife overcome, entirely caught up in, absorbed in, transfixed by the pleasure he is bestowing on her is often a key element of the culminating stimulus to his own climax, pushing him over the edge into orgasm.
   This closing of the eyes (to keep out distractions?) raises an interesting question: is the experience of sexual climax an experience in which a person is “alone”?

Do We Climax Together or Alone?
   For the moment, I am not discussing the question of simultaneous climaxing of husband and wife. I am focusing now on the psychological experience of orgasm.
   Of course, a husband is not literally alone, as he climaxes in his wife. But is he, in a sense, psychologically alone in that moment of intense pleasure – completely absorbed in his own self, his own feelings? And does this in some way undermine the unity of the couple at this moment? Is it a moment that is unavoidably selfish? Is there a paradox that in this physical unity the moment of climax is itself an experience of aloneness or isolation as one is caught up completely in one's own pleasure? I think that it can be that way, very easily. 

  The last moments before climax can also be a moment in which a husband can unite with his wife in more than a physical way.  He can tell his wife, urgently, as he reaches the point of no return, "I'mmm commmming, my love" -- letting her know that he is entering the indescribable moment, one that she has been, is, or will likely be experiencing too, and in this way recognizing his debt to her for having brought him to this moment.  In one sense, at least, it can be equivalent to: "I am coming . . . to YOU, and I want you to know the delight you have been the cause of."   The words spoken just before orgasm can be a conscious stimulus to both self and spouse to enter into the transcendence of the approaching moment.

  As to the actual moment of climax, one way to experience sexual climax is total absorption in one’s own pleasure: one reacts to the experience with “I . . . feeeeeeel . . . soooooooooooooooo . . . gooooooood!
  But the moment of climax, in which it seems that he is totally absorbed in his own intense and overpowering pleasure, doesn’t have to be a moment of total absorption in himself. Whether it is may depend on his whole stance on, his attitude toward, life -- his understanding of reality – his "default" horizon or world.

  The alternative to being alone with himself in that moment is being with God. Being with another human being is not possible (or at least extremely difficult) at this moment, even with his wife – who is the immediate occasion, cause, even location of this pleasure, and toward whom at that moment he feels such deep gratitude – because he is so deeply inside himself at that moment that no other human being can reach there, and be with him there. The only other person Who can be there is God. And the natural response in His presence there is gratitude. That is what makes it possible for sex to be transcendent, to push us beyond ourselves, and, indeed, everything else – to go to the ultimate Reality that exceeds the universe and is, at the same time, at the center of our being, as the source of our being, Who knows us more intimately than we know ourselves.
   So it is also possible NOT to be alone, but rather to achieve union in and during orgasm – above all, through gratitude: One reacts to the experience with “Oh, myyyy Gooooood . . . ..Thhaaaaaaannnnnkk yoooooouuuu!”

   While, as I said, it seems virtually impossible for anyone else to “be there” at that moment, it makes a difference if the wife also has that same attitude or stance toward reality, so that each one of them implicitly knows that the other is experiencing that moment in the same transcendent way.  They know that they are there together, even though at the very farthest reach they are alone with God. In a sense, they can be alone with God, together.
   And this aspect of union can be encouraged or fostered by verbalizing, by speaking, by expressing it in speech. While it might seem that this would diminish the interiority of the moment, it doesn't have to (at least, judging from my experience). The "thank you, God" (or "my God, I love this moment so much") spoken at orgasm is not intended primarily as a communication with the spouse (though it is that incidentally and intentionally) – if it is, it might diminish the pleasure of that moment. It is really the overflow of feelings, the spontaneous reaction of a believer to such an immense gift, talking to God (though knowing, and intending, that the spouse "overhear" that "conversation").

  And, similarly, spoken afterwards, as husband and wife quickly come down from the heights of pleasure, but experience the contented well-being of closeness (that wonderful oxytocin!), words of gratitude and love for each other and to God help anchor them together in a common understanding of what they have experienced together – their deep conjugal union and bond, and its transcendent meaning.