The Nordic region is the world leader in regional coupling of electricity grids and markets. Interconnectors join countries across land and sea, while a common Nordic spot market ensures efficient trade across subnational price zones. This cooperation increases security of supply, lowers system costs and facilitates the integration of renewables. Thanks to this, the Nordic electricity system is one of the world’s most secure, affordable and renewable. Bidirectional trade flows around Denmark illustrate the role of interconnectors in balancing variable wind power, alongside local flexibility (see insight #9). Interconnectors are also important in balancing hydropower in dry years.