Kauai beach
Kauai beach, Hawaii, where From Here to Eternity was filmedCommander John Bortniak, NOAA Corps

A couple's plan for an outdoor romp in the sea ended in agony when they became stuck together during sex.

The Italian couple took advantage of a warm day and an isolated beach in the Marche region of Italy by going for a skinny dip in the sea, and embracing in a passionate clinch.

But the passion soon became embarrassment and pain when they realised they were unable to pull away from one another.

Italian newspaper Il Mattino reported that the man was "unable to extricate himself from the woman due to suction".

A woman who was passing by on the beach came to the amorous couple's rescue.

She handed them a towel to protect their modesty as they sheepishly scramble back on to the beach, still "as one" the newspaper reported.

They were taken to a local hospital, where a doctor freed them by giving the woman an injection to dilate her uterus.

Penis captivus is a rare occurrence in intercourse when the muscles in the vagina clamp down on the penis much more firmly than usual (a form of vaginismus), making it impossible for the penis to withdraw from the vagina.

However, two papers published by 19th-century German gynaecologists, Scanzoni and Hildebrandt had dealt with cases of the condition. Scanzoni's patient was "a completely healthy young woman, married for six months".

She and her husband had to abstain from sexual intercourse because her intense vaginal contractions were "most painful to him and…... did on several occasions end in a spasm…which sometimes lasted more than ten minutes and made it impossible for the couple to separate".