Dubai Police issued a Dh10,000 fine to an airline pilot who hosted a yacht party which breached Covid-19 safety measures.
The force said as many as 25 people gathered on the vessel, with guests ignoring social distancing rules and failing to wear masks.
Police did not reveal when the party was held or its specific location in the emirate.
Action was taken after video footage of the party was posted on social media by some of those in attendance.
Authorities have taken strong action in recent weeks against members of the public and businesses found to be ignoring Covid-19 regulations.
Last month, a Dubai resident was fined Dh10,000 after flouting Covid-19 laws by throwing a party at her home.
The woman and her guests broke physical-distancing rules and were not wearing face masks during the event, Dubai Police said.
The host had also invited a live band to perform at the gathering.
In another incident, a television actress was taken in for questioning by police after footage of her celebrating her birthday party at a restaurant in Dubai circulated online.
The Snapchat video showed Mariam Hussein surrounded by partygoers at a venue in the city's financial district.
Ms Hussein, who lives in Dubai and is Moroccan, said she was given a surprise birthday cake by the restaurant's managers and diners crowded around to take pictures.
She was hit with a Dh10,000 fine and later apologised in an interview with The National.
“I am aware of how strict measures are taken against offenders," she said.
"I would not break them just to celebrate my birthday, but I may have made a mistake by allowing fans to approach too close for pictures and felt embarrassed to reject their requests.”
Officials have warned against large gatherings - both at home and in public - as they seek to drive down infection rates in the country.
The UAE recorded its highest daily total of Covid-19 cases for a fourth day on Saturday as 1,231 infections were confirmed.
