Helen had changed over the last few days from only ever going topless, she had on one day gone completely naked and even let me fuck her while somebody watched us. The holiday was nearly over and on our last but one day we made our daily journey to the beach and Helen looked great. All she was wearing was a long vest and flip flops. As we walked along the sea edge she would occasionly bend over to pick up a shell and give me a good view of her naked bum. My cock was stiff under my swim shorts. Helen headed straight to the secueded dune and we stripped off. Helen had told me she felt quite sexy and liberated. We lay in the sun for a couple of hours,touching each other. We had the occasional male walk by and have a good look at Helen's body. At about 1 pm Helen told me she needed to go into the sea to have a pee. We went down and walked into the sea. As I had a cast on my arm I had to be careful not to get it wet. There were a few other couples already in the sea along with some single men. After about ten minutes I told helen I was going back to the dune. She stayed in the water, splashing about and having a swim. I got back and watched her as she jumped up and down in the waves, her 40dd tits looked great swinging about. A single bloke moved towards her and they started talking as they stood in the sea. After about ten minutes Helen and the bloke turned and started to walk out of the sea. As they came out of the water I saw the bloke had a semi erection, his prick was swinging about as he walked. He and Helen started to walk back towards me, but made a slight detour as they collected his towel and a bag before they walked back to the dune. Helen introduced him to me. He was a young Brit,Mark, 22 yrs old, on holiday with his girlfriend who had gone shopping with her mother who lived in Spain. Helen had taken a him, his muscular body and his prick. We spoke for a while. He told us thet he and his girlfriend always came to the naturist beach so they could get all over tans. Helen suggested she put sun tan cream on us both as the sun was quite hot and strong. She told us to stand side by side as she sprayed the oil on our chests. She rubbed it in and then sprayed my semi erect prick and balls and then sprayed Mark's prick. She gave me a quick rub, but spent some time rubbing the oil around Mark's prick and balls. She got him stiff and started to wank him. She then told him to lay on his back. He laid down and she gave him a blow job. She licked his 8 inch erction, running her tongue up it from , then taking it into her mouth and giving him and good suck, as she run her hand over his muscular chest. I moved behind her and found her clit and rubbed it. As she sucked his prick she began to moan as I pleasuered her with one hand and wanked my prick with the other. Mark then told her he was going to come. Helen then stopped sucking him and proceeded to wank him. He came in a big burst, his spunk flying up his body. Some landed on his chin, the rest on his chest. As he came I felt Helen's body shudder as she came. As Mark cleaned himself up, she wanked me and I came. Mark stayed with us for about another hour and he had a finger of Helen's pussy and she wanked him again while a couple of blokes watched her. She told him to stop by the next day as it was our last day. I will continue later with what happened the next day and night.