Box jellyfish
In Australia (mainly northern; however, box jellyfish can live in subtropical waters as far south as Sydney, with "Carybdea marsupialis" being recorded as far south as Bermagui, Sapphire Coast) the highest risk period for the box jellyfish is between October and May, but stings and specimens have been reported all months of the year. Similarly, the highest risk conditions are those with calm water and a light, onshore breeze; however, stings and specimens have been reported in all conditions.
Chrysaora achlyos
The black sea nettle (Chrysaora achlyos), sometimes informally known as the black jellyfish or sarlacc jellyfish, is a species of jellyfish that can be found in the waters of the Pacific Ocean. Its range is thought to be from Monterey Bay in the north, down to southern Baja California and Mexico, though there are reports of sightings as far north as British Columbia.