Outraged members of the public called police to the beach to arrest the British couple, who were arrested because of their involvement in "a sexual act."
Police are appealing for witnesses after the alleged indecent act was reported on the beach at Shanklin Esplanade.
The woman, from Redhill, Surrey, and the man, from the Derby area, were held on suspicion of being involved in an act of outraging public decency.
The pair were taken to Newport Police Station for questioning and bailed pending further inquiries.
Officers are looking for members of the public who were on Shanklin beach at the time.