Citizens from a hundred countries can stay in South Korea for 90 days with a valid passport. More information in this article...
Citizens of some hundred countries can travel to South Korea for holidays or for leisure with a valid passport. They can stay in the country for a period generally varying between 30 and 90 days. Canadian citizens can stay for up to 6 months. You can request an extension of your stay once you are already on site. You can check out the applied criteria and conditions on the Korea Tourism website.
If you are not entitled to a visa exemption in your home country, you should apply for a tourist visa at the South Korean Embassy or Consulate which is nearest to your residence. You will have to submit a duly completed and signed application form along with your passport, a passport-type photo and any other support documents necessary for the type of visa you are requesting. Fees apply.
Usually, tourist visas for South Korea are single entry. In case of departure from the country, your visa will no longer be valid. If you have to leave South Korea several times during your stay, you can apply for a multiple entry visa before departure or ask for a re-entry permit from the Ministry of justice.