SYDNEY (AFP) - Australia's largest city Sydney will welcome 2018 with a rainbow-themed fireworks spectacular hailing the introduction of same-sex marriage, amid strict security for festivities that kick off celebrations around the world.
More than 1.5 million spectators were packing the city's foreshore to watch tonnes of pyrotechnics light up the night sky in the first major New Year's bash.
The technicolour display will include a rainbow waterfall of fireworks cascading off the Sydney Harbour Bridge to mark Australia's legalisation of same-sex marriage following a nationwide postal vote in support of change.
"This is a fabulous way to see out 2017 - the year that four out of five Sydneysiders said a resounding 'Yes' to marriage equality," said Sydney Lord Mayor Clover Moore.
Hollywood actor Hugh Jackman will add star power with a 20-second gold-and-silver pyrotechnics set, fulfilling a lifelong dream to design a firework for his home town.
AROUND THE WORLD
Celebrations then move across the world to Asia, the Middle East, Africa, Europe and finally the Americas, and dazzling light shows will bid farewell to 2017.
Hong Kong: "Shooting stars" will be fired from the rooftops of buildings in a 10-minute musical firework display
Singapore: Many landmarks are included in the countdown party, with a symphony of light and sound illuminating the waterfront skyline
Jakarta: Some 500 couples will wed in a mass ceremony sponsored by the government, and festivals and bazaars will be held on main roads and at tourist sites
Tokyo: People traditionally spend the evening with their families at home, although many young people head downtown for countdown events
Dubai: The city is replacing its main midnight fireworks with a laser show on the world's tallest tower, the 828m Burj Khalifa, accompanied by music
Moscow: Major boulevards and squares will be decked out to welcome the new year, with fireworks to light up 36 key sites
Rio de Janeiro: Millions will gather on Copacabana beach to watch the fireworks, with many wearing white, the traditional colour to usher in the new year.
TOUGHEST SECURITY IN YEARS
Stricter security will be a key focus amid fears that the huge crowds in public places could be targets for vehicle and other terror attacks.
In Australia, the stronger police presence will include some officers carrying semi-automatic rifles in Sydney and bollards used as barriers against vehicles.
Earlier in December one man was killed and more than a dozen hurt when a man ploughed a car into a crowd of pedestrians in Melbourne.
"You're going to see more police than ever out, it will be our largest contingent... (given) the current security environment," said Victoria state police acting chief commissioner Shane Patton.
Other cities are also preparing for possible threats following deadly vehicle assaults over the past two years in Barcelona, Nice and London.
New York's Times Square celebrations will be guarded by the strongest security presence in years, after two recent attacks apparently inspired by the Islamic State in Iraq and Syria (ISIS) group.
ISIS' defeat in Iraq and Syria was one of the key stories this year, although the Islamist militants remain a threat and numerous attacks around the world were claimed by them or Al-Qaeda-linked groups.
Donald Trump has stolen the spotlight as he made his debut as US President in 2017, with "America first" policies and a bombastic personal style that has shaken up international diplomacy.
The former reality television star is likely to continue dominating headlines in 2018, with escalating tensions over North Korea among a host of global challenges in the new year.
Other political and diplomatic earthquakes set to rumble into 2018 include the crisis in the Middle East between Saudi Arabia and its allies against Qatar, and the humanitarian disaster in Yemen.
In Europe, further talks on Brexit will help shape the region's future trade relationship, while Russia is set to host the football World Cup amid frictions with the West.