USHUAIA, Argentina (AP) _ Thousands of new millennium revelers gathered at the most inhabited southern tip of the world Friday to bid a spectacular goodbye to the 20th-century amid showering fireworks and thumping electronic music.

Thousands braved wipping winds and freezing temperatures to watch a fireworks show along the Beagle Channel marking the onset of the new millennium. The crackling firework displays illuminated a blue-gray sky with hues of yellow, green, and red against a skyline of snow-clad mountaintops.

Ushuaia, the world's southernmost city some 1,945 miles south of the Argentine capital of Buenos Aires and a just 435 miles north of Antarctica, was either a final destination or launching point for thousands of adventurous new millennium revelers.

Some arrived in private jets or chartered planes with ambitions to travel to Antarctica. Others trekked to this city of 45,000 on motorbikes, capping off an across the Americas journey to the most southerly point their bikes could travel.

``I wanted to ride to one of the world's most flarflung places for the beginning of Year 2000,'' said Nat Crewe, a 28-year-old adventure biker who set off from Pruedhoe Bay, Alaska in August.

Four months and 17,000 miles later Crewe arrived here in Ushuaia where he joined dozens of like-minded bikers traveling from as far away as Nova Scotia to bid farewell to the 20th-century.

Bonfires burned bright in the Tierra del Fuego national park where the motorbikers from Germany, England, Scotland, and the United States held their own end-of-the-century party at the end of the world _ complete with spiced wine.

Meanwhile, hundreds of teenagers gathered on the northern shores of the Beagle Channel that slithers through the islands of the Tierra del Fuego pennisula for a rave party. Electronic music blared over loudspeakers as they writhed away the millennium's first hours.

Dozens of celebrators nibbled on $100-a-plate chicken, crab, and pasta dinners inside a turn-of-the-century jail which once housed some of the Argentina's most notorious criminals.

The Ushuaia prison was built in the early 1900s by convicts banished by the government to the country's frosty southern outpost. Tango great Carlos Gardel was said to be among those once condemned to toil in the region's shivering temperatures.

Over 2,000 people poured into Ushuaia throughout the week to climb aboard luxury liners bound for Antarctica for millenium festivites. Sam Blythe, owner of the Toronto, Canada-based tour group Marine Expeditions, had several ships would converge at the island's edge for an unprecendented bash across four boats.

``We wanted the most unique, memorable party in the wildest place in the world,'' he said as the ships pulled out of the Ushuaia port this week.

Following three years of coordinating, Blythe made plans for the ships to converge at a sunken volcano for a 12-hour party that will end with dancing into the morning hours on the deck of the largest cruiseliner. He even chartered ice cutters to shuttle guests from boat to boat.

But few of the adventure-minded partyers could compete with French navigator Andre Bronner, whose new millennium party plans took him to the Isla de Los Estados, a remote island east of Tierra del Fuego. Freezing rains and gusting winds make the island virtually uninhabitable.

Last year, Bronner spent several months on the island, once home to a military jail and now only inhabited by four Argentine naval scientists, building a wooden lighthouse replica that inspired the 1905 Jules Verne book, Lighthouse at the End of the World.

Along with 11 colleagues and friends, Bronner sought to relight the lighthouse as the clock struck twelve.