It has been reported that in the warm, sunny, and usually tranquil beaches of Spain that at least 700 tourists have been stung by small, transparent jellyfish this past week, leading the local officials to rapidly post up warning signs.

The wiggly little invaders have caused “a swimmer’s nightmare,” reports The Associated Press.

The majority of the attacks seem to be occurring the most often near the city of Elche in Eastern Spain, in an area known as Costa Blanca, a rather popular tourist destination for its remarkable white sand beaches.

This past Tuesday alone, 380 people felt the sting from these tiny creatures, comments Juan Carlos Castellanos of the Elche city department for tourism and tourism development.

“In the five or six years I have been in this job, I have never seen anything like this,” Castellanos calmly explains to the AP.

Besides putting up signs warning people of the dangers, officials from Elche are keeping a close lokout for the jellyfish from boats so they can warn the crowds on the beaches when a swarm is approaching.

Meanwhile, just off of the northern coast, in Cantabria and the Basque region, more menacing, and likely more painful, jellyfish-like Portuguese man-of-wars have been inciting their own wave of fear. More than 300 people have had the misfortune of being stun by on those bad boys during the past three weeks, AP comments.

No one knows for sure why the jellyfish are coming up in such immense numbers, but researchers are blaming it on global warming and overfishing practices in the region.