Personnel on board Royal Navy survey vessel HMS Enterprise turned away a man attempting to board the ship during its visit to Cork, Ireland, in a video shared online.
Activist Diarmaid Ó Cadhla was stopped by armed members of the crew after ascending the gangway of the vessel.
Irish Gardaí arrested a male for public order offences at Cork's John Horgan Quay on 16 June.
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He was detained in Mayfield Garda Station, where he was later charged.
A Royal Navy spokesperson said: "HMS Enterprise was making a routine visit to Cork. There was no breach of security.
"Prior to going alongside in Cork, HMS Enterprise had been operating with an Irish Naval Service vessel at sea.
"The Royal Navy thanks the Garda for its professionalism and we look forward to our continued work together."
HMS Enterprise primarily surveys ocean floors but has also taken part in mine detection and the fight against human trafficking.