If seasonal visitors are added to permanent residents, several Greek islands now show population pressure even greater than Attica. Santorini reaches 1,164 people and tourist beds per square kilometer, while Salamina exceeds 1,100, mainly due to the extensive presence of vacation homes. Mykonos, Skiathos, Aegina, Spetses, and Poros follow, all recording particularly high densities relative to their size and the capacity of their local infrastructure.

The data comes from a new study by the Sustainable Tourism Observatory of the Aegean at the University of the Aegean, led by Giannis Spilanis, emeritus professor at the university and director of the observatory.

The research examines the relationship between tourism, construction, permanent population, and the carrying capacity of island regions, highlighting the increasing pressure many destinations face, especially during the summer season.

When tourism exceeds the islands’ limits

The scientists focused on the tourism density index — the number of tourist beds per square kilometer — which reflects the burden tourism places on infrastructure, natural resources, and the environment.

Under the study’s basic scenario, which includes hotels and short-term rental accommodations such as Airbnb properties, Santorini records 863.4 beds per square kilometer, Mykonos 611.4, and Skiathos 381.5.

They are followed by Koufonisia with 278.4, Paxoi with 245.9, Kos with 232.5, and Poros with 217.8 beds per square kilometer.

Overall, seven islands exceed 200 beds per square kilometer, while another 14 surpass the threshold of 100 beds, which according to the European Environment Agency is considered an indicator of heightened tourism pressure.

Particularly notable is the case of Rhodes, which has the largest absolute number of tourist beds, totaling 182,629. However, because of the island’s large size, its density stands at 100.6 beds per square kilometer, significantly lower than that of many smaller island destinations.

Strong pressure in the Saronic Gulf as well

The picture becomes even more severe under the expanded scenario of the study, which also includes seasonal and vacant homes used as holiday residences.

In this case, 21 islands exceed 200 beds per square kilometer.

Santorini reaches 964 beds per square kilometer, Salamina 712, and Mykonos 634.3. High densities are also recorded in Skiathos with 477.2, Aegina with 418.3, Poros with 409.8, and Spetses with 404.4 beds per square kilometer.

The findings show that strong pressure is not confined to the Cyclades but is also evident in the Saronic Gulf, where widespread vacation-home development significantly increases the total burden on local areas.

Limited infrastructure and rising needs

When permanent residents are added to the index, the overall picture becomes even more pressing.

Santorini reaches 1,164.4 people and beds per square kilometer, followed by Salamina, Mykonos, Skiathos, Aegina, Spetses, and Poros.

The study notes that many islands struggle to cope with the increased demand generated during the summer months. Needs for water supply, electricity, waste management, and transportation rise dramatically, while in many cases existing infrastructure is insufficient to support the expanded population.

At the same time, the spread of short-term rentals has sharply reduced housing availability for permanent residents and workers, leading to steep increases in rents and the cost of living.

In destinations such as Santorini and Mykonos, the housing problem is now developing into one of the most significant issues facing local communities.

Only eleven islands increased their population

The same report notes that only eleven islands recorded population growth over the last decade.

Among them are Santorini, Mykonos, Rhodes, and Paros, where tourism development contributed to maintaining or even increasing population levels.

By contrast, other tourist destinations such as Corfu and Thasos experienced significant population decline despite their intense tourism activity each year.

According to the researchers, this demonstrates that tourism growth does not necessarily lead to balanced social and demographic development.

Tourism development without balance

The study’s central conclusion is that tourism significantly strengthens the economic activity of island regions, but by itself does not guarantee sustainable development or social cohesion.

The researchers stress the need for better spatial planning, stronger infrastructure, and more effective management of tourist flows in order to protect residents’ quality of life and ensure the long-term sustainability of the destinations themselves.