Dazzling fireworks lit up Australia's Sydney Harbor, communist Vietnam held a rare, Western-style countdown to the new year, and Japanese revelers released balloons carrying notes with people's hopes and dreams as the world ushered in 2011.
In Europe, Greeks, Irish and Spaniards began partying through the night to help put a year of economic woe behind them. And in New York, nearly a million New Year's Eve revelers were expected to cram into Times Square to watch the midnight ball drop, just days after the city got clobbered by a blizzard.
Police Commissioner Ray Kelly said the city wasn't the target of a New Year's Eve terror threat. But police have a strict security plan in place, with sealed manhole covers and counter-snipers on rooftops.
Miami residents Rodrigo and Maria Lequerich brought their family to New York at the urging of their 13-year daughter, Maria Sophia.
"I saw it on TV all the time and I really wanted to be there in person this time," Maria Sophia said, adding that she was looking forward to seeing a performance by Ke$ha, the event's top musical draw.
As rainclouds cleared, around 50,000 people, many sporting large, brightly colored wigs, gathered in Madrid's central Puerta del Sol square to take part in "Las Uvas," or "The Grapes," a tradition in which people eat a grape for each of the 12 chimes of midnight.
New Zealanders and South Pacific island nations were among the first to celebrate the arrival of 2011. In New Zealand's Auckland, explosions of red, gold and white burst over the Sky Tower, while tens of thousands danced and sang in the streets below. In Christchurch, partyers shrugged off a minor 3.3 earthquake that struck just before 10 p.m.
Multicolored starbusts and gigantic sparklers lit the midnight sky over Australia's Sydney Harbor in a pyrotechnics show witnessed by 1.5 million spectators. "This has got to be the best place to be in the world tonight," said Marc Wilson, 41.
Hundreds of thousands of people gathered along Hong Kong's Victoria Harbor to watch fireworks explode from the roofs of 10 of the city's most famous buildings.
In Vietnam's capital, Hanoi, an estimated 55,000 people packed a square in front of the city's elegant French colonial-style opera house for their first New Year's countdown blowout, complete with dizzying strobe lights and thumping techno music spun by international DJs.
Vietnamese typically save their biggest celebrations for Tet, the lunar new year that begins on Feb. 3. But in recent years, Western influence has started seeping into Vietnamese culture among teens, who have no memory of war or poverty and are eager to find a new reason to party in the communist country.
At Japan's Zojoji temple in Tokyo, monks chanted and revelers marked the arrival of the new year by releasing silver balloons with notes inside. The temple's giant 15-ton bell rang in the background.
In Seoul, South Korea, more than 80,000 people celebrated by watching a traditional bell ringing ceremony and fireworks.
In Dubai, the world's tallest building was awash in fireworks from the base to its needle-like spire nearly a half-mile above. Sparkling silver rays shot out from the Burj Khalifa in a 10-minute display.
In London, higher temperatures after weeks of frigid weather were expected to draw about 250,000 onto the streets. Many planned to line the River Thames to watch fireworks and hear Big Ben toll at the stroke of midnight.
In Scotland, the four-day Hogmanay festival began Thursday night with a torch-lit procession through the streets of Edinburgh. Around 25,000 people took part, marching to the top of a hill to watch the burning of a model Viking ship. Hogmanay is derived from the winter solstice festival celebrated by the Vikings.