Canada is a maritime nation with access to three oceans (Atlantic, Pacific, and Arctic), and shared access to the longest inland waterway system in the world, the Great Lakes St. Lawrence Seaway system of waterways. The map shows approximately 590 major ports, the Seaway (including major locks) and vessel traffic service zones. The Canada Marine Act governs Canada’s port and harbour systems. The ports, comprising the National Port System, have been classified into three major types: Canada Port Authorities (CPAs), regional/local ports and remote ports. The largest ports are the 19 CPAs and 1 harbour commission (Oshawa), recognized by the Federal government as vital to domestic and international trade. The Canada Shipping Act provides for regulations which govern vessel traffic in the 11 vessel service traffic zones.