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Rockies :: Yoho :: Lake McArthur and Mt. Schaffer

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Panoramic view from Mt. Schaffer, looking south at first part of Biddle Horseshoe.  Lake McArthur right with Park Mountain above, Opabin Plateau left

September 29, 2020

Lake McArthur is the largest in O'Hara basin and perhaps the most beautiful.  It is fairly undemanding hike from Lake O'Hara and return time should not exceed 3 hours, making it perfect candidate when time is short and/or not being able to secure access shuttle bus.  Continuing to Mt. Schaffer is more involved, but still feasible as day hike and within domain of competent scrambler.  Scenery is amazing, just like anywhere else in O'Hara area, and larches at Schaffer Lake in late September are particularly spectacular.

From end of O'Hara access road by Le Relais shelter, take signed Lake McArthur trail starting opposite Ranger station.  Within 5 minutes trail enters expansive meadow (take right fork at "Big Larches Junction") and reaches Elizabeth Parker ACC Hut.   Continue straight past Cathedral basin junction then switchback up to Schaffer Lake;  major highlight of the day.  Note huge grass/talus slope above the lake (gallery pic);  some people use this as alternate approach for Mt. Schaffer, but this slope is very steep near the top and not recommended, even for descent.  It is much better to enjoy gentle Lake McArthur trail instead.  Continue straight towards Odaray junction, then take left turn for McArthur Pass by the sign.  Reaching the Pass trail splits into high and low route.  Low route is probably prettier but loses bit of elevation;  high route traverses boulder slopes above with one or two steps that might call for use of hands and is beautifully engineered.  Distances are short and both options are well worth trying out, in a loop perhaps.  They eventually join up at end of larch dotted terrace gently sloping down to Lake McArthur.

Mt. Schaffer is directly above the lake on left (east) side.  It is actually beginning of horseshoe ridge circling high above entire McArthur basin, with towering Mt. Biddle, often beautifully reflected in still McArthur water, being the main prize.  This horseshoe is technical, but hikers/scramblers can still explore the first part.   Hike up grassy slopes initially transitioning into talus (trail) and eventually topping up on terrace above.  Even if not going all the way up it is more than worth getting at least here as aerial views of McArthur basin are nothing short of spectacular.  Continue on cairned trail towards Mt. Schaffer.  This trail does not always lead in best direction and sections are a bit lose.  Staying on crest in lower part works best, then swing climber left when it becomes too steep. Only real scramble bit is class 3 when tackled head on, but it can easily be bypassed on climber right via semi-exposed ledge.  Rest is easy and within an hour from Lake McArthur you should reach ridge start.  Alpine route from All Souls Prospect joins here (5.6).   Summit is ~10 minutes away and is easy scrambling only.  3m rock wall barres the progress, but is easily overcome via little chimney on left side (gallery, class 2).  Next bump is the summit; circle on right (west) side then easily clamber up bits of trail to summit cairn and register.  Views are spectacular, in particular aerial panorama of Lake O'Hara deep below.   It is possible to continue for another 10-15 minutes from the summit, but steep technical wall that requires rope will bare the progress. Return the same way, resisting urge to shortcut directly to Schaffer Lake.

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