The Gravelines nuclear power plant in northern France, the largest in Western Europe, was forced to shut down four of its six reactors due to an unprecedented swarm of jellyfish clogging the cooling water intake filters. The state-owned energy company Electricite de France (EDF) reported that the "massive and unpredictable presence" of jellyfish in the pumping stations responsible for cooling the reactors caused the automatic shutdown starting on August 11, 2025. This rare incident highlights vulnerabilities in nuclear plant operations amid environmental changes, as marine heat waves and rising sea temperatures in the English Channel have contributed to jellyfish proliferation near the coast. The shutdown resulted in approximately 3.6 gigawatts of power being taken offline, with estimated daily losses exceeding $1 million. EDF has stated that safety was never compromised during the event. Restarting operations began on August 13, with one reactor resuming activity and the remaining three expected to come back online gradually over the week, though the restart timeline has been delayed compared to initial projections. The incident underscores the impact of ecological factors on critical energy infrastructure and raises concerns about the resilience of nuclear power plants to such natural disruptions.