Commercial shipping is an example of a tertiary economic activity. Tertiary industries involve the provision of services. Also known as the service sector, this industry includes the selling of goods and provision of skills or services. Other examples of tertiary economic activities include the health service, transportation, education, tourism and retail. As secondary industries have declined, tertiary economic activity has grown and it is now Northern Ireland's biggest employer.

The Odyssey Centre in Belfast contains many examples of tertiary activities: such as bars, restaurants, coffee shops and cinemas.

Here in the centre of Belfast there are more service jobs. This is the Central Business District or CBD. The jobs in this area include transporting and delivering goods and selling goods in shops. The offices and businesses also house tertiary activities such as insurance, solicitors, accountants, banking, estate agents and sales. The services of street cleaning and refuse disposal are also needed in this area. These are all tertiary or service activities. The central area of every settlement in Northern Ireland provides tertiary jobs.

Primary jobs are rarely found in settlements and secondary jobs are mostly found in industrial estates on the outskirts.

Air travel is an example of a service industry that can be found can be found on the outskirts of settlement areas.