Following on from my West Coast Wandering post, here's some notes on the Eldon Range in the SW corner of the Cradle Mt Lake St Clair NP. I should start by saying I have not been to the Eldons myself. These comments are based on map reading and 2nd hand reports from other people who have been there.
To the south and west, the Eldon Range is closely guarded by the deep ravines of the twin Eldon Rivers. To the north and east, long ridges extend towards the wildly remote upper Murchison River.
There are 3 main access routes: Cardigan Flats to the South; Lake Burbury to the west; and the Cuvier Valley to the east. The entire area is essentially trackless so my descriptions will be suitably vague. There are some remnants of explorer tracks from the 1800s but I don't think these are much help. Most walks I've read or heard about in the Eldons are in the order of 7 to 10 days.
A boat trip up Lake Burbury offers the closest access to the Range itself by motorised transport (excluding helicopter of course). From here you are faced with a serious vertical climb of 1,200 metres through fairly inhospitable scrub. I've read about people walking down from Eldon Peak this way but I have not read about anyone going UP this way. I expect it could be quite similar to the side of Precipitous Bluff that rises out of New River Lagoon on the South Coast Track.
The southern and eastern accesses both hinge on Five Duck Tarn which perches precasiously on a ridge above the source of the South Eldon and Murchison Rivers.
From the Lyell Highway, the Collingwood River needs to be crossed and the ridge is climbed from Pigeon House Hill to the much higher Rocky Hill. From here, serious peak baggers will detour west to nab Camp Hill and Last Hill before continuing east to a point midway between Rocky Hill and Pyramid Mountain where you can pick up the ridge leading north to Five Duck Tarn.
From the Cuvier Valley or Narcissus, the rather lengthy approach involves a traverse from Byron Gap over Mt Byron, Mt Cuvier (where peak bagging nuts will detour north to get Mt Manfred), Little Sugarloaf (where Goulds Sugarloaf is a short detour away) and Pyramid Mt. Much of this traverse is very well described in The Abels Volume 1. At the end of this traverse, the aim is to head north to Five Duck Tarn.
From Five Duck Tarn, the ridge is followed north-west past High Dome and Castle Mountain (more peak bagging points) to Lake Ewart at the foot of Eldon Bluff. If you have made it this far, you have survived several days of fairly grueling high altitude traverse. If you have a week or less at your disposal, this is as far as you are likely to get before having to head back. If more time is available, the even higher altitude traverse of the Eldon Range itself lies aheadto the west. This is a long high dolerite ridge leading From Eldon Bluff to Eldon Peak. From Lake Ewart, there is also Dome Hill a few kms north.
This area has some historical significance as early track cut by explorers in the 1800s traversed these mountains. The names Camp, Rocky and Last Hill date from these times. Ewarts track headed north from what is now called Lake Ewart through the depths of the Murchison Valley and over the saddle between Mts Ossa and Thetis to join the Innes Track at Pelion Plains. The northern section of this track can still be followed south from the Overland Track up to old coal mines on the western slopes of Ossa.
Hopefully this entry may prompt someone who has actually been to the Eldons to write in and share their experience.
P.S. I believe Volume Two of the Abels will be released soon. This will cover the Eldon Range and surrounding peaks. Most if the peaks in Volume Two will be in trackless terrain. It will be very interesting to see how the authors approach this.