Boats and barges of every size clog the waterways, most decked out in orange streamers and balloons and piled high with speakers pumping out more beats at an ear-splitting volume.

Even Amsterdam’s world-famous red light district is quiet, with most of those who work here taking the day off to enjoy the revelry that has swept the city.

So what’s all the fuss about?

Queen’s Day commemorates the birthday of Queen Juliana. When her daughter Beatrix took the throne in 1980, she decided to leave Queen’s Day on April 30 as a tribute to her mother, and because her own birthday fell in January when the weather isn’t so good.

The abundance of orange, which has become Holland’s national colour even though it doesn’t appear on its flag, refers to the name of the Dutch royal family – the House of Orange.

While the main event goes on all day on April 30, the night before, known as Queen’s Night, has become an equally massive celebration.

Queen’s Day is a Carnival-style street party, but Queen’s Night is more of a music festival, with a dozen-odd sound stages around the city centre and some of the Netherlands’ best trance and house DJs taking to the turntables.

The Queen’s Night tradition only started in the 1990s, when pre-Queen’s Day riots were an increasing problem in another of Holland’s big cities, The Hague. Authorities convinced the rioters that celebrating was a better way to pass the time, and Queen’s Night was born.

Though it’s the biggest day on the calendar in Holland, the cool thing about this festival is that it’s relatively unknown on the world stage.

Many Dutch people living abroad try to make the pilgrimage home for the national holiday, while the vast majority of locals get involved as well, meaning tourists are a minority.

In any case, it’s easy to blend in – just grab a pint of Heineken, slap on some orange clothes or accessories and join a million other punters succumbing to a little ‘oranjegekte’.

Free to roam

On Queen’s Day it’s impossible to miss the ‘vrijmarkt’ or freemarket – a city-wide flea market where you can find everything from used dentist equipment to home-made treats and vintage clothing.

It’s the one day of the year the Dutch government makes a dispensation where people can trade without a licence and don’t have to pay taxes on their sales.

Locals set up stalls in parks, on sidewalks and in just about any available nook or crannie.

Estimates put the number of vendors at 1.8 million throughout the Netherlands, with the value of the sales topping 200 million euros.

Typically, kids sell their cast-off toys and clothes while entrepreneurs sell food, cold beer, and anything else imaginable.

Prices are negotiable and drop as the day progresses.

» Trevor Paddenburg travelled to Amsterdam with Busabout (0131 557 9393; The Queen’s Day tour costs £199