
[1-Sadlier Mountain and Fortress Lake]
Fortress Lake is located in Hamber Provincial Park in British Columbia, and is accessible only by fly-in, and hiking or skiing over a 24 km (15 miles) route from Sunwapta Falls in Jasper National Park. Hamber Provincial Park has 24,000 hectares.
Trophy brook trout catch and release fly fishing in a remote and private wilderness area. Photos of the sizes of the fish caught in this lake can be seen here.
From British Columbia Parks:
“At high elevation, and with pristine wilderness, this park has excellent angling opportunities, and is prime grizzly and black bear country. A rustic campground is located at the east end of Fortress Lake and several traditional campsites are identifiable along the north shore of the lake. Each campsite has a pit toilet and bear pole for storing food. Because Hamber Provincial Park is an undeveloped wilderness area with no facilities, visitors should be self-sufficient and properly equipped.”
As an added bonus the following are photos of braver and tougher hikers than I who walked to Fortress Lake.

[2-Trail to Fortress Lake from Sunwapta Falls]

[3-Trail to Fortress Lake beside Athabasca River]

[4-Crossing the Athabasca River]

[5-Crossing the Athbasca River]

[6-Trail to Fortress Lake - click to enlarge]

[7-click to enlarge]

[8-click to enlarge]

[9-Crossing the Chaba River as there is no bridge]
These hikers sent the tallest of their group first into the icy water to see how deep it was. However, the reward of reaching Fortress Lake would be waiting.
Sources:
Fly Fish Alberta
http://www.britishcolumbia.com/parks/?id=176
Photo Credits: [1][2][3][4][5][6][7][8][9]-Mr. Hermit CC=nc-nd-flickr.