Distance: 7.4 km (3.0 DOC hours) - Unmarked route, clear - Moderate terrain
Altitude: 1282m to 1645m. Gain: 1002m. Loss: 984m . Gradient: 16 deg (Moderate)
Skills:

Unmarked route, clear (7/9)
Unmarked route, follows obvious geography (river, spur, trail, etc)

Primary, unmapped (2/5)
Route not on maps, but is principal access to hut or along range / catchment

Moderate (difficulty: 3/5)
Occasional moderate climbs

Moderate (difficulty: 3/5)
Low scrub in open or bush / river rocks

Unknown (difficulty: 0/7)
Not specified

None (difficulty: 1/6)
No unbridged river crossings

Unknown (difficulty: 0/7)
Not specified

With a stiff climb directly away from the lake to gain the ridge as comparison, the traverse to Mt Benson is a gently rise.

From the summit, continue NW along the Lockett Range a short distance to SH1672 and a big scree then tussock descent to the base of a greywacke gendarme that forces a sidle on the left (Cobb Valley) side under SH1503. Regaining the ridge, continue to descend (perhaps with a small deviation to tarns on the left) to the 1340m contour where a bluff forces a diversion to the left, dropping into the trees before contouring around to regain the ridge in a saddle.

After climbing a knoll the track swings west then climbs again, swinging back to the north. Passing a small tarn (accessible water, usually), the track rises through a hanging valley (good camping) under Waingaro Peak to the track junction - left and down to Fenella Hut or up and right to sidle under Waingaro on the route to Lonely Lake.

Note: Described in the reverse direction to your journey

From the junction, follow the ridge into a hanging valley (good camping) and continue past a large cairn, descending past a small tarn. Still on an obvious footpad, climb the next knoll and, descending,swing to the left and down into a saddle - a small bluff in front of you.
The track moves into the trees on the right and climbs the side of the bluff then continues in the trees climbing (past another larger bluff) before regaining the ridge. The track follows the ridge until shortly before SH150. where it drops to the right (Cobb Valley side) and sidles under the peak and gendarme into the saddle below SH1672. The scree climb is best tackled by skirting to the right until reaching a rib and following that to the top. Continue along the tops to Mt Benson summit then take the NE ridge (over a few small rocky knobs) until you are above the clearing at the north end of Ruby Lake. Descend more or less directly to the clearing.