In what is believed to be a world first, the boardwalk is made of recycled plastic and composite fibre.

Knox councillor Sue McMillan said the boardwalk would give locals access to the national park.

Cr McMillan said the incline had previously been too steep for pedestrian access, given the site's former use as a quarry.

Beginning at Beech Close, Ferntree Gully, the boardwalk is 75 metres long. It was constructed by Replas Recycled Plastic Products.

The company said the unique construction would revolutionise the design and production of boardwalks.

Cr McMillan said composite fibre and recycled plastic would last for more than 40 years without maintenance, and would not rust, split, rot or be targeted by termites. "The structure is environmentally sustainable, it's durable, and above all, safe," she said.

The completion of the boardwalk fulfils a 1992 agreement between CSR and the former Shire of Sherbrooke, when the idea of a pedestrian link across the quarry site to the National Park was first floated.

It was funded by CSR as part of the development of the Peregrine Heights estate.