I was in the basement of a house which was filled with water. I kept swimming back and forth from one end of the house to the other. I thought I was alone until I heard a loud splash. I turned and saw Mr. B. (a married man who lived next door to my family over 5 years ago and I used to baby sit with his daughter.) He swam over to me and I realized that he was naked. I was also but it didn't seem to be wrong. We swam about together and eventually he kissed me and later we had intercourse under the water. I asked him where his wife was and he said she would be down soon. She did come down very soon and saw us together. This did not shock or even surprise her. I kept swimming back and forth until I was very tired.