Thousands of people are expected to take to the streets of Belfast later for the Pride parade.
Ahead of the parade, Belfast Lord Mayor John Finucane received the first Pride flag that will fly from City Hall.
The rainbow flag was delivered down Belfast Lough on a flotilla of boats blasting their horns to cheers from onlookers on the banks on Friday evening.
Mr Finucane helped erect the flag at City Hall early on Saturday morning.
It will be the first time a Pride flag has flown from the landmark building.
PSNI Assistant Chief Constable George Clarke and US Consul General in Belfast Elizabeth Kennedy Trudeau were among those who attended the Pride of Sail event.
A flotilla on Belfast Lough last night with boats filled with Team Pride volunteers and supporters brought the Pride flag in to Belfast last night and that flag will over Belfast City Hall for the first time ever today! Happy Pride! #RightsNow #bproud2019 pic.twitter.com/HXToHZ0TGv— Belfast Pride (@belfastpride) August 3, 2019
Speaking ahead of the event, Mr Finucane, who is leading the parade, described it as one of the highlights of his year as mayor.
"This was an excellent event organised by Belfast Pride, they had a flotilla coming down the Lagan to present me with one of the original Gilbert Baker Pride flags to mark the significance of the Pride flag flying over the City Hall for the first time in our history as a city tomorrow and to celebrate what I think will be the biggest and the best ever Pride festival in Belfast," he said.
Meanwhile, the head of BBC Northern Ireland addressed the "confusion" around staff members attending Belfast Pride saying the broadcaster is not participating corporately.
The BBC has faced questions over impartiality - given that same-sex marriage is a contentious political issue in the region - since announcing staff in the organisation's BBC Pride group would be attending the event.
A memo to workers issued last week said staff would be participating in the annual Pride parade wearing BBC-branded T-shirts.
A statement also mentioned BBC Northern Ireland in the context of employees taking part.
BBC NI director Peter Johnston acknowledged there had been "confusion" about the "terms and basis for BBC staff involvement in the Belfast Pride parade 2019".
He said while members of the BBC Pride staff network - an employee-led initiative - would be taking part, BBC NI as a corporate body would not.
"We know that there are legislative issues specific to Northern Ireland in relation to same-sex marriage," he said.
"These raise important considerations for the BBC in the context of its editorial guidelines, including the requirement to maintain due impartiality within our output.
"None of this means that members of the BBC Pride network cannot be involved in Pride festivities in Belfast, but it does require BBC Northern Ireland to avoid creating the impression that it has a position on matters of political contention or controversy.
"The BBC's editorial guidelines provide clear advice in this regard. It is on this basis that BBC NI will not be involved corporately in the Belfast Pride parade and that individual programme brands will not be represented."
Ulster Television (UTV) staff members will take part in Belfast Pride for the third time on Saturday.
The ITV-owned organisation participated in the event for the first time in 2017, with several well-known UTV broadcasters taking part.
A spokeswoman for UTV said the company was proud to be involved.