By Tristana Moore BBC correspondent in Berlin

It is one o'clock and the train is packed. Some German teenagers are sitting opposite me clutching their cans of lager and bottles of champagne.

Don't panic and just have fun

Organisers

"Life is great, I don't know how to dance, but who cares - we're here to dance."

They try to chat up a Spanish girl who is here with a group of friends.

Scantily-clad women performed erotic dances

A woman wearing a golden bra and not much else laughs in the corner of the carriage as her boyfriend, who is heavily made up, blows his whistle. "Welcome to the Love Parade!" he screams out. "I've arrived."

From across the other side of the carriage, Sergio Galvan, a 26 year-old from Murcia in Spain, tells me he has come to Berlin to listen to the techno music. "It's the largest techno party in the world and I wouldn't miss it for anything. There's nothing like this in Spain, Britain, or anywhere."

Excuse for a party

At Berlin's Ernst Reuter Platz, we all pile out.

The police are out in force. More than 2,000 officers are on duty - just in case - but no one is really expecting any trouble.

Life is great, I don't know how to dance, but who cares - we're here to dance

The square is already filling up with revellers - and colourful floats. In all, around 40 floats, from 11 countries, are taking part in this year's Love Parade - with DJs from all over the world.

Hundreds of thousands are taking part (AFP)

The slogan is "Access Peace" - something to do with love and peace, so the organisers tell me, although I must confess the whole event just seems like simply a good excuse for a big party.

The music is thumping and the dancing starts.

It is two o'clock and the rave has officially begun. There are some amazing costumes - from women dressed as cow-girls, to men on stilts and transvestites, all trying to outdo each other. Everyone seems to have a water-pistol and a whistle. It is incredibly loud.

Techno know-how

Date: 1987 Electronic dance music that features a fast beat and synthesized sounds usually without vocals or a conventional popular song structure Source: Websters

For some it is too much already. Lars Gruner, who is from Bremen, is lying semi-comatose on the ground. He has been up all night. "I've been partying for 24 hours. I came last year and loved it so much I had to come back."

His girlfriend is lying beside him on the grass - she yawns and then suddenly gets up and starts a trance-like dance. The energy of the music is contagious.

Undaunted

Many thousands - some say up to a million - people are believed to have attended this year's Love Parade. There were fears that some of the party-goers might have been put off from coming to Berlin after the German tabloid newspaper, Das Bild, reported last month that al-Qaeda were planning to attack the city.

But German police have strongly denied these reports. The message from the organisers was very simple: "Don't panic and just have fun."

Many displayed their national credentials

From the Ernst Reuter Platz and from the Brandenburg Gate, the party wound its way up to the Tiergarten Park in the centre of Berlin. By late afternoon and, despite some intermittent showers, thousands of people gathered around the Siegessaule monument, dancing, drinking and showing off.

The party is not over yet - you can keep on dancing through the night at clubs across Berlin. Then there is the horrible bit - cleaning up - and dealing with the complaints of some Berliners who do not like all the rubbish that has been left behind. But who cares when it has been such fun?