Suburbs of Palma in Majorca are seeing an increase in tourists, despite few hotels being located there.
Local residents believe they know the reason for the unexpected increase and are planning to take matters into their own hands.
Spain has been gripped by growing anti-tourist protests, as local communities vent their anger at the effects of mass tourism.
One of the chief complaints has been the proliferation of holiday rental apartments, which are promoted on online platforms.
Activists say the increase in rental apartments is forcing locals out of the property market, as prices spiral ever upwards.
Jaume Garau of the Palma XXI association told the Majorca Daily Bulletin that he had a good idea as to why more tourists were turning up in Palma's suburbs.
He said: “The center is saturated and so there is now tourist accommodation away from the centre.
“And when we see so many tourists staying in these areas, it is because there is a lot of illegal supply.
“All the legal places are full, so they go elsewhere: to illegal accommodation.”
In Palma renting out apartments to tourists is prohibited but, despite this, the business appears to be booming.
Joan Nadal, a representative of the Menys Turisme, Més Vida platform which organized a massive anti-overtourism protest in Palma earlier this year, said: “We know that there are illegal tourist properties in our neighbourhood.
“They do not pay taxes and create nuisance for neighbors because of anti-social behavior.”
Some of Spain's most popular cities have slowly introduced new rules to limit the number of holiday rentals.
Despite this, statistics from the Spanish government show that the number of tourist apartments has increased by nine percent in the last year, with more than 340,000 now registered.
This means in some cities there is one tourist rental for every 1.5 square kilometers and for every 139 locals.
Most of the rental apartments are owned by big businesses and not private individuals, research has shown.