Strata 17 Swimming (Pleasure and Pain) The Book of Immersion by Sarnia de la Mare

Welcome to Immersion, you have reached Strata 17 Swimming (Pleasure and Pain)

Pain and pleasure are sensory and emotional experiences generated by the human brain. These experiences are driven by chemicals, situations, and lived experiences, all of which reinforce these mammalian phenomena that originate from nearly identical internal processes rooted deeply in biology. Endorphins can both block pain and produce euphoria, activating and stimulating areas of the brain such as the limbic system and the prefrontal cortex—regions that also respond to music and passionate romantic experiences. The mammalian central nervous system includes specialised neurons for pleasant touch, which transmit pleasurable or ecstatic sensations along the spine. In contrast, machines do not possess these intricate systems and therefore do not experience pain when threatened or physically harmed. For the same reason, they cannot feel the pleasure of touch. At best, they can simulate such responses, but any such imitation would exist solely for a human's benefit, not for the machine itself.
Flex removed his clothes and left them in an untidy pile on the grass.Renyke, still somewhat unstable on his feet, followed suit.
'Come on, don't be scared,' shouted Flex from the water, 'I'll teach you how to swim.'
The blue water was cold and yet exhilarating. It rippled over Renyke's skin like a moving shroud. He stared at his hands floating on the surface of this strange organic compound. The water stroked him like a lover and he remembered Shabra.
'This is how she feels....' Renyke thought, holding his closed eyes toward the sun.
Such warmth and pleasure he had never felt before. His skin was eager for more.
Suddenly, Flex ducked him under the water, and after what seemed the longest time, Renyke finally got the hang of staying afloat by copying Flex’s tread water techniques.
There seemed a lot to learn all at once.
A few panicked moments nearing the bottom of the fjord had caused a fear so deep, so frightening, and so alien to anything that Renyke had known since his manufacture. 
'If you want to swim under the water,' Flex explained panting, 'take three slow deep breaths before thrusting downwards. Then, slowly let air out as you swim deeper…for equilibrium. 
It's important to stay calm. Panic wastes air. You will find you can hold your breath longer under water than above it. 
If your ears hurt, you went too deep. Oh and remember to come up for air in case you pass out and die.’
Flex laughed at his own joke, and Renyke smiled. Maybe he was starting to understand his friend’s humour at last, though death by drowning did not sound fun at all.
Prepared with this alarming but good advice, Renyke disappeared to play with fishes and check for mermaids, recalling his seemingly prophetic dreams. 
Maybeline and Flex played tag amongst the reeds and the warm sun rays hit the river with a blanket of human promise.
'Oi!' Flex shouted with urgency, exiting the water at speed.
Renyke watched his friends muscular naked body as it made haste through the reeds. He wondered why he never noticed the beauty of human skin and the intricate interplay of muscle and sinew as it danced over bones.
Renyke and Maybeline watched the commotion on the grass.
'Pleases don't hurt me, pleases don't hurt little Nigel.'
A small, pale, and strangely formed man, around three feet tall, wriggled his feet violently as Flex held him upside down from a considerable height.
'What were you doing with our stuff?' demanded Flex. 'I saw you Mr. *Freak. Don't be taking me for no and *fucksyfool.'
'Look, look