Helsinki Pride Parade marchers began gathering around midday on Saturday at Citizens' Square before beginning a 2.5-kilometre walk to Kaivopuisto Park at 1 pm.
Festivities at the park ran from 3 to 6 pm. Among those appearing onstage were the event's official patron, Social Democratic MP Nasima Razmyar, rapper Paleface and Canadian comedian Jamie MacDonald.
35,000 attendees, same as last year
Billed by organiser HeSeta as "a celebration of gender and sexual minorities" and "Finland’s largest culture and human rights event", the annual event last year drew some 35,000 participants.
In cool, cloudy weather on Saturday this year's initial numbers appeared to be substantially smaller, said police.
"There are fewer people than last year," Chief Inspector Jari Taponen of Helsinki Police told Yle around 1.20 pm. "Not 30,000 so far at least, closer to 20,000."
He noted that more people were joining the march as it proceeded through the city centre.
Around 2.30 pm Helsinki Police tweeted: "Estimated 35,000 participants in #Pride2017 parade."
Close scrutiny for counter-demonstrators
Taponen said some notifications of counter-demonstrations were filed in advance. He said these activities were under careful scrutiny. He said it was unclear how many of the pre-announced counter-demonstrations would actually materialise.
In 2010 three men with ties to the far right were convicted of spraying tear gas and pepper spray at Helsinki Pride marchers on the main shopping street, Aleksanterinkatu.
Taponen later told the newspaper Helsingin Sanomat that one person was detained near a "Finland First" group close to the Music Centre. The individual was carrying a plastic bag containing excrement.
”Threats of an attack on the Pride parade had been made on Facebook, so they were under special observation," Taponen said.