None of those stung by the jellyfish-like creatures were in serious condition but the flurry of stings on the beach forced authorities at the beach in Benidorm to take action.
Bathing in the sea at several beaches was banned for up to two hours while the creatures were removed from the surrounding waters.
Yellow flags were then flown on the Levante, Poniente and Mal PAs beaches to warn bathers.
The man o'war – not strictly a jellyfish but a floating colony of microscopic hydrozoans – has tentacles that can reach 30 yards long and are barbed with a sting that typically cause painful welts lasting up to three days.
In some cases the sting can cause an allergic reaction and in rare cases, heart failure.
Even when washed up on the sand the stings still contain venom.
Up until a decade ago, they were rarely sighted in the Mediterranean but have become a more common occurrence.