THOUSANDS of people slipped into town in a novel way at the weekend in Grand Rapids, Michigan - travelling three city blocks on what promoters say is the world's longest inflatable water slide.

The puffy blue and yellow slide is about 170 metres long. Water from a fire hydrant kept the vinyl track slippery.

A section of the great water slide in Grand Rapids, Michigan. Credit:tbird31/Twitter

A ride on the slide was free. Yet the service was only temporary; it was to be dismantled after two days.

Still, its builders say the $30,000 slide is sturdy enough to last 20 years with good maintenance and careful storage, so the plan is to reinflate it yearly for as long as it holds up.

Rob Bliss, who conceived the idea, said his events were about ''creating a unique moment in time''.