Travelers to Europe, mark your calendars (and bring your raincoats). On June 15, activist groups across southern Europe are planning to stage protests against tourism. Although the precise form of those demonstrations has not been decided, it’s a pretty safe bet that water guns will be involved.

Last weekend in Barcelona, about 120 representatives from Venice; Lisbon; Palermo, Italy; and a dozen other cities joined leaders of the Southern Europe Network Against Touristification in calling for a coordinated day of action to raise awareness about what they called “the urgent need to limit the growth of tourism.” The tactics discussed included marches, picketing at airports, obstructing tourists’ entry to historic sites and blockading tour buses.