From the start point (at waypoint ‘START’) head E/SE along Ridley Road for almost 500m. Veer left, off-track at ‘1’ to leave the road. Soon pass through a thicket of sheoaks and reach a small rounded granite outcrop after about 300m (at ‘2’). Cross the top of the outcrop and veer SW to climb initially very gently through mixed open forest via ‘3’. The route crosses a small gully near ‘3-1’ and the slope steepens to reach a ridge at ‘4’. Veer southward at ‘4’ to walk upslope close to the crest of the ridge, veering slightly downslope to the west (to ‘5’) to bypass small granite outcrops and boulders. Then continue very gently upslope SSE (just west of the ridge crest) mainly through open thickets of sheoak (which mostly block the otherwise good potential views of Mount Yetar to the west). After about 300m cross the ridge crest near ‘5-1’ and descend the NE flank for a very short distance to a small granite ledge (at ‘6’) which provides a view across the Helena River valley to the summit area of Mount Billy, less than 2km NE. Then return to the ridge at ‘6-1’ (backtracking a little to bypass a dense patch of shrubs) and continue SSE. After ‘6-2’ the sheoak thickets give way to open wandoo woodland near the summit of this unnamed hill. (With an elevation of 341m this hill is 42m higher than Mount Billy). Continue SSE (to ‘7’) and bypass the small laterite-capped actual summit area upslope to the west. At ‘8’ cross the head of a deep gully which plunges eastward from below the hilltop. Then follow south flank of the gully eastward, staying initially on the bare upper slope, with the rocky laterite-capped ridge top just to your right. After about 250m, at ‘9’, descend steeply down the gully flank to cross the stream course at ‘9-1’. Climb around the north flank to reach and explore a small, but conspicuous rock outcrop ‘Sentinel Rock’ (WalkGPS informal name), at ‘10’. Then head SE to ‘11’, then eastward, crossing an old vehicle track at ’11-1’ and Bumper Road (vehicle track) at ‘12’. Continue eastward through open woodland. Continue eastward through wandoo woodland across the broad valley floor, then onto a broad ridge which rises gently. After crossing a narrow stream gully, veer NE-ward at ’13’ and continue gently uphill along the NW edge of the spur ridge, soon gaining a view back to the hill to the west which you just traversed. At ’14’, at the head of a gully which plunges NW, veer eastward again and climb more steeply uphill to ’15’. Then veer NW again and after about 200m of further climbing, reach the hill-top (elevation 327m). Continue NW across the hilltop and pass through a narrow belt of sheoaks to reach the top of a granite slab (at ’16’). Follow the slab downslope to the ENE for about 200m. Near the foot of the slab (at ’17’) veer left (north) to soon follow the east bank of a small stream gully. After about 200m (at ’18’), veer NW to soon reach another granite slab (at ’18-1′) which has a view to Mount Billy to the NW. Follow the slab eastward across a low ridge and soon re-enter open wandoo woodland and cross Bouncer Road (dirt road at ’18-2′). Then follow a vehicle track across a nearby deep gully at ‘19’ and continue eastward via ‘20’ and ‘21’ to cross another nearby gully. Then head ENE/NE along slope via ’21-1’, bypassing the dryandra (Pingle)-covered uplands above a laterite breakaway on the right. Veer east on a small ridge (at ’22’) to reach a granite slab (at ’23’) in a small valley. Veer north to cross the slab and climb through heath and low shrubland onto a broad ridge (at ’24’). Head NNE, mainly along slope, bypass denser shrubland if necessary. Then begin descending, soon reaching the upper slopes of an outcrop at ’24-1’. Descend the outcrop northward and reach Ridley Road (at ‘24-3’). Follow Ridley Road gently downhill to the NE until the road veers due eastward after 300m (at ’25’). Then leave the road to head north, off-track across the sandy valley floor for 300m, picking your way easily through a shrubland of swamp tea-tree to reach another dirt road (at ’26’). Turn left to follow the road initially NW and then westward as it begins curving to follow the nearby Helena River course. Ignore the side road at ’26-1′ then turn right at ’27’ to follow another side road northward, firstly crossing Helena River by a ford. The River course is likely to have water in it (even during an unusually dry spring) but by detouring through the sedges slightly to the left of the ford it is usually possible to step across without getting wet boots. Continue north along the dirt road, crossing Ball Road (dirt road at ’28’), and soon the road approximately follows the fenceline of the adjacent farmland to the east. The road starts climbing more steeply uphill and veers slightly NW away from the fenceline (at ’28-1’). Then leave the road (at ’29’) to head approx. westward and gently upslope across a generally rocky area and through patches of mixed forest (mainly sheoak) and small granite-floored clearings. On leaving the denser forest, after ’29-1’, soon cross a small gully which becomes more deeply incised upstream. After crossing the gully to ‘30’ on the south bank, head SW-ward up the ridge above the south bank, climbing through open wandoo woodland. At ’31’ veer right to continue NNW up the ridge to ‘32’. From there soon start descending gently WNW down the westward-sloping hillside. Or see Option below, if you wish to follow the shorter 15.5km route across Mount Billy itself.) Continue via ‘33’ and reach the south bank of a small gully at ‘34’ Veer left (WNW) along the gully and reach an old vehicle track at ‘35’. Turn right to follow the track. Within 30m, at ’35-1’ you will pass a fascinating cluster of old iron-mongery and other relics abandoned in the woodland; large metal cages, old drums, a mound of charcoal, and excavated trenches. This is a significant, as yet unregistered historic ‘charcoal burner’ site where charcoal was once produced. It is well worth taking some time to explore around this site to visualise what an active site it once was and how the 6-8 day carbonization process would have been carried out. Then continue NW along the vehicle track and turn right when it meets Bell Road at ’35-2’. Follow Bell Road to Yarra Road, Cross Yarra Road and head WNW off-track. Veer right (NW) at ‘37’ and climb gently uphill through a sandy area of fairly open heathland. Meet a vehicle track at ‘38’ and turn left to follow the track more steeply uphill though jarrah forest. When the track veers sharply to the right (at ’39’), as a short-cut you can continue NW and off-track through heathland to rejoin the track again after only 50m (at ’40’). The track then crosses a deep gully and climbs westward up the western bank. At ’41’, leave the track to continue westward, initially crossing a small south-sloping spur ridge at ’41-1’. Continue westward along slope, and traverse the upper slope of an outcrop after ’41-2’ at the head of a small valley which opens to the SE, with good views 4.5km across forest to the low hills SE of the Helena River valley, previously visited along this walk route. At the western end of the outcrop after ’41-3’, re-enter tall heath/shrubland to cross a small gully. (Follow animal tracks through the very short section of possible scratchy shrubland and stay upslope to avoid the denser areas.) Then at ’42’veer left (SW) along slope back into open woodland and soon gain a view through the trees to Mount Yetar, 4.5km to the SW. From ‘43’ head down slope WSW/SW via ’43-1’ and ‘44’. Then at ‘45’ veer right to follow the southern side of a deep gully WSW (via ’45-1′). At ’46’ turn left to head SE along slope around the hillside via ‘47’. Cross a stream course after about 300m at ’47-1’ then continue across open grassy slopes at the head of a gully which deepens to the south. At ’48’ turn sharp right to head south along the eastern flank of the gully. Reach a small granite outcrop (at ’48-1′) with another view to Mount Yetar. Then continue SSE along the steepish eastern flank of the gully (to ’48-2′), then down the crest of the SW-sloping ridge to meet Yarra Road (at ’49’). Cross the road to an old, dug-up/mounded vehicle track and follow the track SW to cross the Helena River course at ’49-1’ to get back to the start point on the south bank. If the River is flowing you can instead follow Yarra Road and Ridley Road back to the start point from ‘49’.
Option 1, Shorter walk option, including Mount Billy summit (~15.5 km): If you wish to follow the shorter route across Mt Billy itself, after waypoint ’31’ instead of continuing upslope, head westward along the edge of the laterite-capped hill top and then descend to an outcrop at ’32-alt’. Then follow ’33-alt’, ’35-alt’… etc to cross Bell Road and climb to the summit area of Mount Billy at ’39-alt’. Then descend via ’40-alt’ …etc to rejoin the described walk route at ‘49’ near the end of the walk. This option reduces the total walk distance by 1km.