Lake Louise is a great destination any time of year. During the summer months you can go out on the lake in a rented canoe, or hike along its western border and beyond, all the way to the source of the lake high in the mountain if you're up for it.
There is also a very popular hike that rises up the mountain immediately to the west of the lake. It's a great hike for those in reasonable health - you gain a lot of altitude and the view at the top is excellent, but it's slope is gentle enough for most. There is also a tea hut near the top where you can get great food and drinks.
In the winter months be sure to check out the ice sculpture competition!
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