Citizens of most countries (including USA and EU) need a visa to travel to Russia. However, nationals of some countries do not require a visa to travel to Russia. Here's a current list of those countries below (some are subject to special conditions):
Argentina
(can stay up to 90 out of 180 days for tourist purposes.
business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Armenia
(can stay up to 90 days)
Azerbaijdan
(can stay up to 90 days)
Belarus
(unlimited)
Bolivia
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Bosnia and Herzegovina
(up to 30 days for tourists and up to 90 days for other visitors. need to present the original
Russian visa support invitation to the Russian Immigration authorities)
Brazil
(can stay up to 90 out of 180 days for tourist purposes.
business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Brunei
(up to 14 days for Diplomatic and Service passports holders only)
Chile
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Columbia
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Croatia
(up to 90 days in 180 days period for the holders of Diplomatic and Service passports only)
Cuba
(up to 30 days, holders of biometric passports only)
Dominican Republic
(up to 90 days for the holders of Diplomatic and Service passports only)
Ecuador
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
El Salvador
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Guatemala
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Honduras
(can stay up to 90 out of 180 days for tourist purposes. business visa is required when staying longer than 90 days or when traveling to Russia for work-related, commercial or diplomatic activities)
Hong Kong
(can stay maximum 14 days without a visa)
Iceland
(up to 90 days for the holders of Diplomatic and Service passports only)
Israel
(up to 90 days stay,
the original invitation is required to be presented to the Russian Immigration authorities upon arrival. Visa free regime does not apply for Diplomatic and Service passports holders.)
Kazakhstan
(up to 90 days)
Kirghizstan
(up to 90 days)
Republic of Korea
(up to 60 days for the tourists)
Macedonia
(up to 30 days tourist and up to 90 days for other visitors. The
original travel invitation is required to be presented to the Russian Immigration authorities upon arrival)
Mauritius
(up to 60 days for tourist or business purpose)
Moldova
(up to 90 days)
Mongolia
(up to 30 days stay for the holders of diplomatic, official and foreign passports. In case of consequent trips, total amount of days spent in Russia cannot exceed 90 days in a period of 180 days from the date of first entrance)
Montenegro
(up to 30 days. visa free regime does not apply for Diplomatic and Service passports holders)
Mozambique
(up to 30 days for the holders of Diplomatic and Service passports only)
Nicaragua
(up to 90 days of stay)
Panama
(up to 90 days in 180 days period)
Paraguay
(up to 90 days in 180 days period)
Peru
(up to 90 days in 180 days period for tourist purposes only)
Citizens of Serbia
(up to 30 days with biometric passports obtained after April 9th, 2008. Diplomatic or Official passport holders without accreditation in Russia can stay up to 90 days. Visa free regime does not apply for Yugoslavian passports holders)
The Republic of South Africa
(up to 90 days for the holders of Diplomatic, Official and Service passports only)
Thailand
(up to 30 days. Holders of Diplomatic and Service passports can stay up to 90 days)
Tajikistan
(up to 90 days)
Ukraine
(up to 90 days)
Uruguay
(up to 90 days in 180 days period)
Uzbekistan
(up to 90 days)
Venezuela
(up to 90 days stay. Visa free regime does not apply for Diplomatic and Service passports holders)
USA, EU, UK, Canada, Australia:
You will not need to get a visa if you are traveling to St. Petersburg for up to 72 hours on a cruise ship or on ferries from Helsinki and Tallinn with
St. Peter Line. You will however need to book a tour with them, be accompanied by a guide, and you will have to sleep on the ferry. If you want to sleep outside of the ferry, you would need to present the invitation issued by the hotel you're staying in. You also need to limit your stay to the central area of St. Petersburg.