Lake McArthur is located in Yoho National Park above Lake O’Hara. Starting at Lake O’Hara we took the Big Larches Trail and then followed the high traverse with a small rock climb to get to the plateau where the lake is located. Lake McArthur is a stunning sapphire blue, which is different colour from all the other neighbouring lakes. I am told that the unusual colour is due to the fact that this lake is 279 feet deep. Mount Biddle towers above the lake and the lake holds bits of the mountain reflection. The view is absolutely beautiful!!