What's behind Spain's anti-tourist water pistol protests?

Last weekend saw protesters take to the streets in their thousands in Barcelona and Mallorca, their message going viral as they squired bemused tourists with water pistols.

In Barcelona they also set off smoke bombs and chanted "tourists go home," while some of the signs read 'Your AirBnB used to be my home,' and in Mallorca one read 'Rich Foreign Property Buyers Go Home.'

But why?

After all, Spain's tourism numbers are a huge success. The country is the second most visited country in the world after France and is expected to take the top spot within 10 to 15 years.

Millions come for sun, sea, gastronomy, culture, shopping, and relatively low prices, making Spain a global tourism powerhouse.

The industry accounts for over 12 percent of the country's GDP and employs close to three million people, helping drive predicted GDP growth to 2.5 percent this year, more than twice the Eurozone average.

On the island of Mallorca, 30 percent of employment is in tourism.

Spain is on course to receive 85 million visitors this year and is having a moment with the Chinese market too, analysts predicting a 36 percent rise in Chinese tourists this year compared to last year.

That's good news for Spain's economy because they spend more per person than any other tourist.

Spain's locals priced out of their own cities

Yet locals say gentrification and too many tourists have sent house and rent prices soaring, locking them out of their own cities.

They want a different, more sustainable tourism that doesn't cost the roof over their heads.

The Spanish government has vowed to address the problem. In Barcelona rent caps have been introduced while the Prime Minister Pedro Sanchez announced a 100 percent tax on foreigners buying property in Spain.

But successive corruption scandals have Sanchez's government hanging by a thread and some proposed legislation may never see the light of day.

Rent prices have doubled over the past 10 years and one in four Spanish renters cough up 40 percent of their salary just to keep a roof over their heads.

In Madrid's Plaza Mayor tour groups stay in the shade to avoid the blazing sunshine, temperatures already well above 30 degrees Celsius.

This iconic 16th century square has seen everything from public executions to Placido Domingo concerts. Now it's a must-see stopping point on city walking tours.

Madrid's combination of sun, heat, history, architecture, and outdoor dining, is a draw, along with its vibrant cultural offering and pulsing nightlife.

Tourists sip sangria in the Plaza Mayor, a drop of the good life, while the country's beaches are already seeing the summer waves of arrivals.

Striking the balance between maintaining Spain's tourism success story and protecting the local way of life is key. And that balancing act is becoming increasingly difficult to manage.