Tsakos Energy Navigation Ltd is a seaborne transportation service provider for crude oil and petroleum products. Its carriers cater to national and international independent oil companies and refiners. The company generates revenue through charter contracts with its clients, which include time, bareboat and voyage charters, contracts of affreightment, and pool arrangements.Tsakos Energy Navigation Ltd operates crude oil and petroleum product tankers which provide marine transportation services for national, major and other independent oil companies and refiners. It also transport liquefied natural gas.