A beach in Sinaloa has been closed after hundreds of visitors were stung by jellyfish both in the water and on the beach.
State Civil Protection chief Francisco Vega Meza said that closing Maviri beach in Topolobambo bay was necessary to protect visitors because the creatures are usually not visible.
Yellow and red flags have been placed near where the jellyfish have been seen.
Because jellyfish prefer warm water with high salinity and usually live 30 to 60 kilometers from the coast, the slightly cooler temperatures and lower salinity near the coast create a natural barrier.
But this year, less rain than usual has meant warmer, saltier coastal waters and a more welcoming environment for jellyfish near the beaches. Authorities hope that the start of the rainy season will reduce the salinity and drive the jellyfish away from shore.
Between June 8 and 11, almost 500 people were treated for painful jellyfish stings, mostly on their legs.
The beach will remain closed at least until Monday, when authorities will reevaluate the situation and decide whether to allow visitors to return.
Vega said that stings can be treated by washing the affected area with sea water and using cold compresses. Anesthetic cream with lidocaine can be used to control the pain.
If a victim experiences cramping, muscle spasms or fever after being stung by a jellyfish, medical attention should be sought immediately.