According to a friend of mine runs the Thailand box jelly fish blog states; Research into box jellyfish in Thailand is sort of but not really happening - there is awareness and acknowledgement in scientific circles, there is commitment but there is little money and minimal action. Still, there is slow forward momentum especially at a medical level though there's a long way to go. No clear picture has developed as to habitat and habits. The Australian experience is invaluable but the situation is different. It took many years for action to occur in Australia also, there was a lot of misinformation, resistance and apathy.
Box jellyfish do swim, not float, and while influenced by conditions they have a visual system that can help them navigate around obstacles such as rocks and human legs. There are different types of box jellyfish known in Thailand including the lethal Chironex, Irukandji and Morbakka.
With this information in mind, it may be useful to follow the link below on the stinger suit picture and check out some stinger suit options for children.