If someone shows interest and you are not interested then simply give him flat hands indication, and he should gracefully retreat. Its a polite way of saying no, and in places such as this, no means just that. But if someone approaches and you like what you see, stand with your feet apart and put your hands on your head, inviting him to remove your towel or clothing then intimately touch and feel, making it cleat that his advances are welcome. Having allowed him to touch you, he will expect the same in return, then see where it leads!