The Three Sirens by Irving Wallace

Reveals the experiences of an American anthropological team - men and women from varied backgrounds, of different ages, driven by their own secret desires - on a Polynesian paradise called The Three Sirens. Caught up in a culture where sex is completely uninhibited, where the enjoyment of physical love is spontaneous and guilt-free, each American finds himself confronting his own deeply entrenched fears, repressions, and sexual taboos.

Paperback, 1964

Goodreads: 3.72