New requirements for tourist entry to Canada
Since March 15, 2016, visa-exempt foreign nationals (including Swedish citizens) who fly to or transit through Canada will need an Electronic Travel Authorization (eTA). Exceptions are U.S citizens and travellers with a valid visa.
You must apply online at the Canadian Immigration and Citizenship website before you travel: http://www.cic.gc.ca/english/visit/index.asp The form consists of basic personal information found in your passport and some questions to establish admissibility to Canada. There is a CAD$ 7 application fee, payable with credit card at the time of application.
Read more on the Canadian Immigration and Citizenship website.
This applies to travel by air only.