The SafeSwim site has issued a hazard alert for Piha Beach on Auckland’s west coast for bluebottle jellyfish in the water, Newshub reports. Their venomous tentacles cause an extremely painful sting which raises red welts which can last several days. Swimmers are also warned to take care over water quality issues at several beaches due to high levels of faecal contamination – exceeding national guidelines for swimming. In particular, there is a “very high risk of illness” at Mission Bay after a wastewater overflow in this area.