A 150-metre pedestrian suspension bridge, believed to be the longest in the Southern Hemisphere, is proposed to enhance the Wild Mersey trails at Latrobe.

Meanwhile new trails continue to open among extensive work going on at the St Helens network.

Latrobe Council has announced Bridge Pro Engineering as the successful tenderer to design Australia's longest pedestrian suspension bridge across the Mersey River at Warrawee Conservation Area.

The aim is to enhance the network's mountain bike experience and create an iconic tourist feature in Latrobe.

A draft design will be prepared along with an environmental impact assessment.

Mayor Peter Freshney said the council has been developing the Wild Mersey trails since 2015.

"To have the opportunity to work with a Latrobe-based company to design what will be an iconic piece of infrastructure that is a record for the southern hemisphere is really exciting," he said.

The council said the result would dwarf Australia's longest suspension bridge at Northam in Western Australia, and become the longest in the Southern Hemisphere.

"The long-term plan for council has always been to construct a high-level bridge across the Mersey River that is not susceptible to the impact of flood events like that experienced in 2016."

Meanwhile, 200km to the east, new trails are on the agenda for the St Helens network.

The start of the Blue Tier Trail at Poimena has been realigned.

The 2.3km section takes riders to a junction from where they can either head west on the Blue Tier Trail to the Weldborough Hotel or east, on the Bay of Fires Trail to Swimcart Beach.

All riders get to enjoy a vista over the coast regardless of which trail they decide to tackle.

The old start will be converted back to a walking track while emergency kilometre markers will be installed on the Blue Tier Trail.

The Dreaming Pools is a new trail opening on Saturday.

Starting on Loila Tier, the 27km blue adventure trail will take riders on an exploratory journey of the St Helens back-country.

Starting at an elevation of 360m, it traverses ridge lines and gullies of tall iron bark forest with a flowing mix of climbing and descending and stunning views to the south.

It has a total gain of 490m with a 650m descent and features a run through natural rock pools on Constable Creek and the chance to admire multiple waterfalls.

Construction has also begun on a multi-user track around Georges Bay in St Helens, linking Lions Park to the town centre, due to open at the end of October.

The extension includes new gravel track, an elevated cycleway and a whale bone-design bridge that ends on the St Helens Wharf.