From Spain comes a technology that seems to come out of a science fiction film: an invisible electromagnetic shield capable of blocking jellyfish before they reach the swimmers. No net, no chemical products dispersed in the sea: just a floating device that creates a barrier of electromagnetic fields. The electromagnetic field seems to disturb this very system: the pulsation slows down, the movement weakens and the animal loses the ability to move forward normally. If a huge mass of water pushes a swarm towards the coast, will the electromagnetic field really be able to stop it? The massive proliferations of jellyfish, the so-called jellyfish bloomshave become an economic and environmental issue.