Swizec's answer is good, you technically need a visa. If you can afford to be kicked out of the country and not be allowed back in for a long time (10 years in the US), then it might be worth the risk of not getting the visa. But, if you can't risk being banned, or even if you just like to obey the law, you should get the visa, especially if it's easy... which it is for a lot of countries.