Box jellyfish
Although the notoriously dangerous species of box jellyfish are largely restricted to the tropical Indo-Pacific region, various species of box jellyfish can be found widely in tropical and subtropical oceans, including the Atlantic Ocean and the east Pacific Ocean, with species as far north as California ("Carybdea confusa"), the Mediterranean Sea ("Carybdea marsupialis") and Japan (such as "Chironex yamaguchii"), and as far south as South Africa (for example, "Carybdea branchi") and New Zealand (such as "Copula sivickisi").
Chironex
Chironex is a genus of box jellyfish in the family Chirodropidae. Their stings are highly venomous, and have caused human fatalities. Based on present knowledge, the genus is restricted to the central Indo-Pacific, ranging from to southern Japan to northern Australia.