This creature is found in Australian tropical waters during the summer months. It is often referred to as the box jellyfish because of its cubic shape. Roughly the size of a wine cask, it has a simple branched tentacle, flowing from each corner of the cube, which is extremely dangerous. In fact, it is considered to be the most poisonous creature in our seas. A sting can cause death within minutes. Radio warnings are given when Sea wasps are sighted, and intending swimmers are well advised to change their plans.