Back of the Lake is Banff National Park's premier rock climbing destination. Ultra classic routes are spread across a Quartzite Band on the opposite end of Lake Louise. It is a quick walk to get there, and the crag offers something for everyone. Get here early though, because the parking lot fills up quickly. If you arrive after 9 a.m., just save yourself the hassle and park at the overflow lot outside of town.
Bow Valley Sport and Banff Rock are the best guidebooks for the area. Select Climbs of Western Canada is acceptable, though it is pretty out of date by now. While many folks leave their trad racks at home, it's worth bringing it along as it gets very busy and often it's a good way to get climbing while you wait for your favorite sport line to clear.
If you haven't climbed on quartzite, it's a lot of crimps and rounded horizontal cracks. Get ready for plenty of steep pumpy moves, even in the 5.6 range. The crag is notoriously sandbagged compared to the other crags in the area. Especially beginner routes tend to feel harder.
There are a whole host of classic routes. Main attractions would be Air Voyage and Wicked Gravity (5.11a), but further on you'll find Chocolate Bunnies from Hell (5.11b), DEW Line (5.11c), Jason Lives (5.13a) and Bloodsport (5.11b), Mister Rogers (5.11b), Duck of Death (5.11b) and Liquid Sky (5.11c). Sonnie Trotter's incredible route, The Path (5.14), continues on past Wicked Gravity and is worth just looking at.
The crag is set up starting from the closest to the hotel as follows;