Stockholm Police seized the man after the Silja Galaxy ferry returned to Stockholm on Sunday.
“A woman reported to personnel on board that she had been raped,” police spokesperson Ola Österling told Sweden's TT newswire.
Ferry staff then held the man throughout the return trip so that he could be handed over to Swedish police.
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In 2016, four 19-year-old men were found innocent of raping a woman on a student party cruise between Stockholm and Finland.
The case was one of a string of high-profile sexual assault and harassment cases involving young immigrant men that year, which were seized upon by anti-immigrant and right-wing media.