The Athabasca Oil Sands Deposit is the largest petroleum resource in the world (1.6 trillion barrels, 315 billion recoverable with current technology).
[These two facts are not unrelated. The Alberta government is heavily dependent on oil & gas revenues, and from 1982 - 1992 ran huge deficits while oil prices were low. The recent strength in oil prices, combined with the fiscal discipline of Klein's government, have enabled us to pay off our debts.]