Modern tantra (aka "neotantra") is a type of sexual activity based on a very old set of discoveries about the human body and mind:
The "Tantric High"
The first discovery is something many people are vaguely aware of if they've had marathon sexual encounters: If you are deeply relaxed and remain sexually aroused for an extended period of time, you begin to experience a sense of euphoria. I call this the "tantric high," because it's similar to the "runners high" and has a similar underlying cause (a buildup of endorphins and endocannabinoids , plus PEA in the case of sexual arousal). You could also call it the "honeymoon effect," since it describes the blissful goofiness experienced by many newlyweds back when people didn't live together before the wedding and many honeymoons turned into sexual marathons.
When this first starts to kick in, you're already experiencing a lot of pleasure anyway, so distinguishing between the two can be hard, but most people start to feel that euphoric sensation after around 20-30 minutes, and it grows stronger over time until it eventually hits a saturation point. By the end of a three-hour tantric ritual, it can be pretty intense. I've had people who use grass and hash tell me it's both mellower and more intense than either of those.
Prolonged and Expanded Arousal
The second discovery is also no surprise to people who have experimented with extended sex: the longer the arousal period, the longer and stronger the orgasm or series of orgasms (other things being equal). We're not talking about comparing two different people here, but rather one person having a quickie versus the same person having an intentionally prolonged period of intense arousal before reaching orgasm.
The third discovery uses techniques shared with Kundalini yoga: through disciplined control of your attention to regions of your own body, you can spread the normally localized sensations of sexual arousal beyond the genital area to the rest of the trunk and beyond. Given enough time, skill, and concentration, the orgasm that finally occurs seems to come from the whole body at once, making it much broader and more powerful than any ordinary orgasm.
Sex for Thrills vs Sex for Pleasure
The fourth discovery is more complicated. Humans seem to have (at least) two different pleasure systems keyed to sex. One involves sex with an element of risk, tension, anxiety, even a bit of fear. Pretty much everyone experiences this type of sex first, because our first times are almost always at least somewhat tense and scary. Any time you don't know your partner extremely well, there's some tension, some element of risk, of failure or rejection. When it's successful, it's exhilarating, like sky diving or riding a roller coaster.
In a culture in which young people form many short-term relationships, this is what they learn to expect from sex. When they are with one partner too long, they start feeling vaguely dissatisfied. Desire fades. The thrill is gone. And they interpret this as "falling out of love," so they decide that it's time to break up and go looking for another partner. Over time, it gets harder to recapture the excitement and the intensity, so they start exploring rough sex, sex with strangers, sex in dangerous places, and so on. This is sex for thrills, not sensual pleasure. As a shorthand, I call this adrenaline sex.
The other way to experience intense pleasure from sex is based on the exact opposite approach. Instead of being fast, rough, tense, risky, and thrilling, it is based on slow, safe, gentle, sensual immersion. Start with a safe, familiar setting and a partner who loves you and trusts you as much as you love and trust them. Make sure you have no time pressures and there will be no interruptions. Begin with a long relaxing bath or shower in which you wash and dry each other. Follow that with deep meditation and long, sensual, full-body massages. There should not be a shred of tension left at the start of sexual activities, just deep relaxation and enjoyment of the pure sensual pleasure you give each other.
Because all of these elements tend to trigger the release of oxytocin and tend to promote pair-bonding, I call this oxytocin sex or pair-bonding sex. It's not necessarily better than adrenaline sex, but it is at least AS enjoyable, and - very importantly - it is sustainable. Unlike adrenaline sex, the thrill doesn't fade with familiarity. Indeed, it requires familiarity. It's great sex that depends heavily on knowing, loving, and trusting each other.
Transcendental Experiences
The fifth discovery is the reason that tantric sex got so entangled with religion: an extended and successful tantric ritual can trigger a powerful transcendental experience for many people. This usually comes in one of two forms. The first is an intense and very convincing sense of merging with one's partner in body, mind, and spirit, and of experiencing everything both of you are feeling from both sides at the same time. I won't argue about whether it is "really" happening at some spiritual level - I'm pretty sure it isn't - but it does feel completely real. It's also an absolutely amazing experience!
This feeling of union is quite common among veteran tantric couples, but the other form of transcendental experience is much less so. This is a full-scale, transcendental, oneness-with-the-cosmos experience in which a person loses all sense of physical boundaries. The descriptions of this experience are very similar to the typical descriptions of both ecstatic religious enlightenment and good LSD experiences.
https://soundcloud.com/daniel-angel-6/here-and-now