German sauna culture has a particular etiquette. Nudity is expected and usually required. Some people say this is because chemicals from the swimming pool might evaporate but it was the rule long before people worried about such things.

Being nude in the company of strangers is supposed to be a liberating experience that breaks down barriers. It is not a sexual experience, or at least it isn't supposed to be and nothing of that sort has ever happened to me. Except of course that one time, which was also my first time. Not my first time in a sauna, the first time I had sex.

It happened at the particle physics summer school in the Black Forest. Two weeks of good food, beautiful scenery and quantum chromodynamics. The last part was not entirely my thing, I was just there to provide tech support. So when everyone else was listening to a lecture on the current state of the search for the then missing top quark, I decided to find some company, preferably female my own age. I couldn't leave the building and the coffee bar was empty, the spa my next choice. 

The only other guest in the pool was a slender woman in her early 40s with long blonde hair. Seeing me arrive, she asked if I could turn on the heat in the sauna as I went past.

The pool was small and I could barely swim four strokes before reaching the other side. After twenty minutes, I decided it was time to try out the exercise machines. As I climbed out of the pool, the woman followed.

"The sauna will be ready for us," she said. Then, removed her swimsuit, washed off the pool water with the hand shower and disappeared inside.

Taking this as an invitation, I stripped off my trunks and followed her. She unfurled her towel and lay down on top of it. I sat on mine, arms awkwardly draped across my legs so as to provide concealment without making the effort too obvious.

We chatted inconsequentially, (something I later discovered to be a breach of sauna etiquette). Anna was a single mother on holiday with her daughter. She didn't say where she came from, though her accent suggested somewhere in Germany. Each time I tried to find out more about her, I found I was telling her more about myself. Yes, I was with the school, no, but I was not a physicist, I hadn't even started university. I was there to manage the computers. Couldn't the physicists do that themselves? Probably, but I knew how to fix them when they didn't behave.

As we were talking, I suddenly realized I had been staring at her naked breasts. I looked down at the floor instead only to be gently chided.

"Look, look all you want," she said, "or am I too old to interest you?"

I laughed as I tried to find the words to respond. Anna stood up and turned sideways to me, showing her full breasts and perfectly flat stomach.

"Do you like it?" Anna asked.

"I like it a lot," I responded.

The sauna was narrow with two rows of seats facing each other, an upper and a lower tier on each side. The entire inside of the sauna was visible through the glass door, albeit dimly due to the smoked glass. Another guest or a member of staff could enter the pool room at any time and see us.

I was seated on the lower tier where it was slightly cooler. Anna rose to sit immediately opposite me on the upper tier and spread her legs wide.

Even thirty years later, my cock still stiffens at the memory. A neatly trimmed triangle of hair on her mound ended just above her clitoris, like an arrow pointing to the prize. Her outer labia were pink and hairless, the inner closed around the main event like a stage curtain.

Unable to find words, I let my hands fall to my sides to reveal my fully erect cock. Anna rewarded me with a smile, then placing her index fingers either side of her slit, gradually parted her curtain.

I stood up and kissed her full on the mouth, our tongues meeting. Her nipples touched my chest and her hands wrapped around my cock.

"We must be quick!" Anna insisted.

We wasted no time on preliminaries, we both knew what we wanted and were both more than ready. Anna lowered herself onto my shaft and suddenly I knew what fucking a woman felt like: it felt good.

I barely lasted a dozen strokes before my seed erupted inside her. As my prick deflated, Anna pulled me close in an embrace that probably took longer than the act itself and thanked me profusely.

At last, Anna released me and sat back on the bench.

Slowly and deliberately, I kissed her gently on the forehead, then on each nipple and then between her legs.

"There isn't time," Anna protested. But her protests quickly turned to sighs as my tongue worked her slit, tasting her juices mixed with my own. When my inexperienced tongue finally found her clit, the sighs got louder and so I continued there. Eventually her back arched and she gripped my neck tightly between her thighs, half throttling me in a silent scream.

Anna barely paused to catch her breath before heading to the waterfall shower, an infernal contraption that empties a tank of ice-cold water onto the victim when they pull a rope. A literal bucket of cold water on any hopes I might have had of further amorous activities with her.

Anna left as I waited for the tank to refill. I might well have given the experience a miss, only a girl of about my own age appeared and started showering for the sauna. 

'Perhaps it will impress her,' I thought as I pulled the rope.

It was worth it. But that is another story.