You hum it son, and I'll SLAY it...

Fans lap up 10-hour onslaught of hard, fast and heavy music at NZ's first punk and metal festival. Photo / Steven McNicholl

The sound of pestilence spews forth from a bunch of long-haired lumberjack-looking types up on stage.

For non-believers it might sound like noise pollution, but for the masses gathered at Auckland's ASB Showgrounds it's the sweet sound of Canadian power metal band 3 Inches of Blood.

Welcome to the first No Sleep Til Auckland festival, a one-day metal and punk extravaganza with 16 international and local bands conjuring up a blood-curdling din for 10 hours.

Headlined by thrash metal pioneers Megadeth, the festival also includes Celtic punks the Dropkick Murphys from Boston and Gwar, a tribe of hideous mutant metal freaks from the US.

It's still only mid-afternoon and already the mosh pit is lethal and sweaty as the inside of the hangar-like venue starts to brew with intensity.

There's a good six hours before Megadeth hit the stage - and it's about to get more lethal.

"I wanna see some crowd surfing," shrieks singer Jake Luhrs from Pennsylvanian screamcore act August Burns Red. "We got some security guards up here looking pretty bored."

With that the kids go to it and a large whirlpool of people forms - it's called a "circle pit" in these parts - as it carves out a giant crop circle in the crowd.

And it gets even more mad when menacing five-piece Suicide Silence set up a "wall of death".

That's where the crowd split to either side of the room and then run at each other when they get the word - like a mass, no-holds-barred bull rush.

Dangerous? Yes. Irresponsible? Yes. Fun? Hell, yeah, especially if you're young, fit, and a little unhinged by the music. And no one seems to get hurt, even the guy with a plaster cast on his arm.

The punters are a ragtag bunch from the many and varied circles of metal and punk - it's a meeting of the tribes.

There are plenty of black band shirts, with names ranging from Megadeth to the Ramones, there's the odd spiky mohawk, and girls with coffin and ghoul bags bouncing around on their backs.

As children, North Shore couple Hayley O'Connor - "the punk girl" - and Jesse Atkins - "the hardcore kid" - used to come to the showgrounds for the Easter Show.

Now the 28-year-olds are here to see some of the bands they grew up with as kids such as Megadeth and punk veterans NOFX.

"The Big Day Out tends to over-sell but this is more grassroots ... and everyone is being really well behaved," O'Connor says.

Well, not that well behaved because it's not that sort of music. It's hard, mostly fast, and always heavy - and that's what the masses are here for.