There's a few interesting places to stop on the one hour drive from Marlo to Lakes and they're just off the highway.
The first is Boggy Creek Gorge.
Just a few minutes walk from the carpark, you find yourself looking down into a deep gorge, surrounded by dense bushland. Boggy Creek begins in the Alps and flows through the gorge, down to lake Tyers.
We didn't do a long walk, but there is some info from Visit Victoria here on a 12km walk you could do.
Lake Tyers itself is lovely. Good for boating, canoeing,
fishing and camping. The lake is separated from the ocean by a narrow
sand bar, forming a tidal lake when the sandbar is broken.
Nowa Nowa is a tiny town in between Boggy Creek and Lake Tyers, and home of the historic Stony Creek Trestle Bridge. The 276m long/ 19 metres high bridge was built in the early 1900's to serve the railway line.
You can walk, or cycle around the bridge and it is part of the East Gippsland Rail Trail. Check their site for rides in the area.