This is the story of what happened on a family holiday many years ago. Our friendship with Marjorie and Ken began before we married, and so we had enjoyed attending each others weddings. We both had families, they had three children, girls - Kirsty and Helen, one year apart, and a boy Ian, three years younger, while our two boys were the same age as Kirsty and Helen. It was natural therefore that we enjoyed occasional family holidays together. Because Ken had to move with his job, we didn't see them for three years, until we arranged a family holiday to Spain - nice villa with pool, in a rural setting 10 miles from the coast and the high rise places packed with Brits in the summer. The eldest children were now 18 and headed for university, so this might be the last opportunity to holiday together as whole families. Kirsty - the eldest - was blonde and a little taller than her sister Helen, not quite so blonde, but with the same shoulder length haircut style, and both had inherited the good looks and figure of their mother, Marjorie, who I had often masturbated over, but never had the chance to fuck. Of course the girls' figures were slimmer than their Mum's now that Marjorie had filled out a little (but in proportion). The first week or our trip was very enjoyable, very warm weather, kids getting on well, the pool was proving very popular. We had a routine of going to nearby resorts or cities, every few days, to provide the chance for each family to enjoy time on their own. After a week, this was amended so Dads and boys could go while Wives and Girls stayed at the villa. Returning from our "Boys" outing, my wife Rita had mentioned to me that they had all taken the opportunity to go topless (well it was quite hot), and Kirsty and Helen had gone further and swum nude. I must admit this made me horny, and thoughts about seeing Marjorie's full bosoms on show had me hard. On the second Tuesday the whole group was supposed to go to the coast (where it was cooler), but I had a fall outside on the patio by the pool, and twisted my ankle, so I begged off the daytrip to take it easy, rest the leg, drink some wine and have a long siesta. They all began collecting things to take with them, and to sort out who was travelling in which car, etc. They were ready to go, when I noticed that Kirsty was not with the party. "She has a headache and is staying in her room", Marjorie reported. "Leave her in peace, she will be fine." Off they went, and the villa was serene and quiet. I found a spot in the shade behind the pool, and made myself comfortable with a book and a bottle of chilled white wine. An hour later, I was as chilled as the wine, and more than a bit drowsy, and I dozed. I was wakened by the sound of splashes in the pool, and was upright in a jolt. I rummaged for my specs, they were on the floor somewhere. Without them I could not make out who or what was in the pool. When I finally found and put them on, I could see that it was Kirsty swimming up and down. I relaxed, took off my specs, emptied my wineglass, and went back to my book. After ten minutes, Kirsty tired of her swimming and climbed the steps out of the pool, fetching her towel from a nearby lounger. While I watched her I could see well enough to know she was naked, but not well enough to enjoy the sight. Now wrapped in her towel, she came towards me. "Sorry if I disturbed your sleep." She said. "I have slept myself, and my headache is much better, and I thought the pool was too good to waste, I hope you don't mind." "Not at all, Kirsty, I probably should prepare some lunch, are you hungry?" "Just a salad for me please, but I would like a glass of that wine you are drinking." "I don't see why not, you old enough to drink, you fetch a glass, while I tidy up here." She strolled off to the kitchen for a glass. I watched her go, her long legs on view, almost up to her buttocks, with her towel covering only between her chest and her bum. She was having a significant effect on my cock, and I had to adjust my shorts. Kirsty was fair-skinned and the Spanish sun was strong, so when she returned, I filled her glass with wine, finishing the bottle. "You should stay out of the sun." I advised. "You're right, but I would like to get a better tan, how about you help me put some sunscreen on." I picked up the sunscreen, and said "Turn around, and I will do your back." Kirsty obliged, and perched on a chair beside my lounger facing away from me, she loosened her towel, and let it drop to her waist. I poured some cream on my hands, and began applying it to her offered back. My cock was now fully erect, and the feel on her gorgeous skin beneath my hands was electric. I managed to complete massaging her back, and gave her the sunscreen, "Here, you best finish yourself now. Go inside, while I go for a dip." Instead of gathering her towel around her, Kirsty stood up, then picked up her towel. She smiled at me, walked to the villa and the kitchen, her towel still in her hand, her naked form flaunted for me. Was she flirting with me? God help me! I now had the memory of her young breasts to add to her skin sensation, making me rock hard. I leaned against my lounger, and hauled myself upright, taking care to protect my ankle. I dropped my shorts and hobbled naked to the pool. "Oh, I forgot to ask, how is your ankle Uncle Ben?." Stupidly, I half turned, "Not too bad thanks", before realising that I had provided Kirsty with a profile showing my raging erection, in all it's glory, and I clocked her gaze and grin before rushing and falling into the cool water. Kirsty was now a young woman, tall and slim, she had developed curves in all the right places, and she had, I think, been deliberately showing me her body, and my cock had responded accordingly. The pool had the desired cooling effect and my erection subsided, so I quickly dried myself, wrapped the towel around me, and headed for the kitchen. I made a salad for lunch, and Kirsty found another half empty bottle of wine in the fridge, so we sat and ate in the cool of the kitchen/diner. Our damp towels were now starting to feel uncomfortable, so I was not surprised when Kirsty said:- "I think we should put the towels in the sun to dry, so we can use them again later. No need for either of us to be shy, we have seen each other naked." What was I to say, how could I respond? To refuse would be churlish, and would create more tension, whereas to agree was accommodating, if a trifle risky. "OK." was all I could muster, as I finished my lunch, offered my wineglass to Kirsty for a toast. We clinked glasses then drained our drinks, and together stood and let our towels drop to the floor. I picked up the towels, and took them outside, placed them on a couple of loungers, and casually walked back inside, my semi-hard cock swinging from side to side. As I washed the lunch things, Kirsty dried and put away. I tried to concentrate on the washing up and limit my gazes upon her nubile form, but my cock insisted on an erection. "I have seen an erect cock before, you know." She smiled at my discomfort. " Are you sunbathing this afternoon?" Changing the subject. "Of course, now I am properly creamed, I can sunbathe, and work on my tan for an hours or so." I recalled the feel of her silky young skin as I had creamed her back for her. Her hair was all muzzled, she had dried it from her swim, but not combed it out. "Best comb your hair." I offered. "You're right." And off she went to the bedroom she shared with her younger sister Helen. I took a cold beer from the fridge, and headed for the patio and pool, and moved my lounger to avoid the sun, now high in the sky. Making myself comfortable, I lay back and started reading my book - for some reason, I had read the same page four times now. Minutes passed, then Kirsty appeared, hair neatly combed, and she laid on her lounger a couple of metres away from mine. She was quietly pretty as well as sexually stunning, with even features reminiscent of her mother. The afternoon sun made it hot and I was glad for being out of clothes, it was definitely more comfortable, and being so hot, my cock had subsided to a persistent semi; at least until I looked across at Kirsty, and saw her sprawled on her lounger, feet on the floor either side, so legs wide apart, and her young pubis with downy blonde hairs, pussy lips on show AND OPEN - WHAT A BUTTERFLY! Seeing her open, and with a sheen of glistening juices, my penis was immediately hard as nails, and before I knew it I had rubbed myself slowly a few times. Kirsty was looking and her eyes widened. "Sorry." Such a lame comment, but what else could I say? Kirsty put her free hand on her crotch, and fingered her pussy, rubbing two fingers up and down before lifting them to her mouth, and sucking them dry of her juices. Her fingers returned to her cunt, and this times rubbed up and down, then she pushed them inside herself, before stretching out her arm to me. "Mmmmmm. Have a taste." The wine, the beer, the sight, and I was up and sucking her fingers before I knew it. Her taste was exquisite, and I closed my eyes to concentrate on her scent, taste and juices. As I was stood over her, Kirsty quickly withdrew her hand and grasped my throbbing cock. The silence was punctured only by the soft swish of her hand around my member. My left hand decided her right breast was a must-visit location, and gently massaged this pert mound, pinching her puffy nipple. She responded with a moan, sat upright, and lowered her head, and before I could stop her, three inches of my erection had disappeared into her mouth. The next two minutes were a blur, all I can recall is that she said "My room" as I carried her in my arms inside the villa. There were two beds - "which?" I asked, and she just said "Left." So I moved to the left bed. Naked on her bed, my hands explored her soaking lovehole, as she writhed on my fingers, then my cock. "I'm on the pill." Just was well. Our tongues played our bodies surrounded and penetrated. It was glorious, and she had the special talent of tensing and clamping her vagina on my erection. I mounted her as she lay on her back her legs wide and ready to cross behind me, then we swopped places, and she rode me, then spoons. We slowed our fucking, then took a rest. I had not cum yet, but Kirsty had a number of whimpering and shaking moments, if not outright shouting orgasms. We rested in each others arms, until I rose for another beer, and a wine for Kirsty. "This is not my first time; and it was very nice, thank you, Ben." "You're welcome." My mind wondered how to deal with this, a mistake, did I take advantage, would she tell, would she hate me, would it be our secret? Whatever. Neither of us could take it back, and so we spent the rest of the afternoon enjoying each other, before having a naked swim in the pool and cleaning up before our families returned. I did not cum inside Kirsty, but gave her a mouth/faceful as the climax of our adventures, just after she had a shattering climax herself. It is an event burnt deeply into my memory, a one-off but it has turned out not a memory to regret. We attended Kirsty's wedding, twelve years later, a while enjoying a dance with the bride, she whispered, "Thanks for the Spanish Holiday."