The off-trail portion of the route crosses high, open alpine flats between the Thunder Lake and Lion Lakes basins
A steep, 660' climb from Thunder Lake levels off near this tarn, whose outlet forms Fan Falls below
The route scales a very steep ridge with excellent views over Thunder Lake
Maintained travel resumes on the grassy northeast shore of Lion Lake #1
A well-formed social trail connects Snowbank Lake with the maintained trail at Lion Lake
Crystal clear tarns dot the broad expanse between drainages
The maintained trail leads to the Thunder Lake inlet area (pictured here), where you'll veer north to begin the steep climb toward Lion Lake
If pressed for time, it's easy to skip Snowbank Lake and continue on a relatively flat line to Lion Lake #1 (pictured here)
You'll have a good view of Boulder Grand Pass (12,061') from high points over Thunder Lake, and the challenging couloir that must be scaled to reach it
While the lakes are worthy destinations by themselves, open, relatively easy alpine travel between them is the route's true highlight
There are no designated backcountry campsites at Lion Lake #1, though limited zone camping permits are available
Snowbank Lake sits under Chiefs Head Peak (13,579') along the Continental Divide
Trio Falls drops between Lion Lake #2 and Lion Lake #1
Hikers can minimize impact on sensitive alpine vegetation by walking on rock slabs and in single file whenever possible
Thunder Lake (10,574') sees heavy traffic throughout the summer and early fall, but few continue beyond it to Boulder Grand Pass, Falcon Lake or over to the Lion Lakes
Hikers must cross Lion Lake's rushing inlet to pick up the maintained trail on the far side
Lion Lake is distinguished by flat, grassy meadows around much of the shore
I hiker stands over a tarn on the cross-country section between drainages
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