The European Union's climate observatory announced that the oceans in the world set a new surface temperature record at 20.96 degrees Celsius (69.7 Fahrenheit).
Ocean surface temperature reached 20.96C on July 30, according to the ERA5 database, while the previous record was 20.95C in March 2016, a spokesperson told AFP.
The samples tested excluded polar regions.
Oceans have absorbed 90% of the excess heat produced by human activity since the dawn of the industrial age, according to scientists.
Globally, the average ocean temperature has been besting seasonal heat records regularly since April.
"The ocean heatwave is an immediate threat to some marine life. We are already seeing coral bleaching in Florida as a direct result. I expect more impacts will surface," said Piers Forster of the International Center for Climate at the University of Leeds.
