The Rennex Walking Track in Kosciuszko National Park near Jindabyne is at a lower elevation than some of the more famous walks, but offers a bit of variety if you’ve had your fill of alpine scenery. It is a 13km return walk on mostly flat terrain at roughly 1650m of elevation, and passes through subalpine woodland, heath and grasslands. There are views back up towards Australia’s highest ground from a few vantage points.
It is named after the engineer who built the road up to Mt Kosciusko, and who died from pneumonia in a blizzard. Track notes are on the NPWS website. It’s described as challenging but I don’t remember it being that difficult.