Diving has been gaining in popularity in recent years with spectacular dive sites in tropical waters. Before anyone goes diving, they should learn about the risk factors associated with the exposure to hyperbaric conditions and also the risks from exposure to marine life. Apart from amazing views of the coral reefs, divers may be astonished by the magnitude of marine species diversity in local waters, ranging from predators (sharks, barracuda, moray eels) to venomous or stinging fish (jellyfish, anemones) and sea snakes. If travelers are unprepared and know little about the existing risk factors, a diving trip that was much looked forward to may turn out to have some very unpleasant consequences. The article describes the most common marine species which divers can come across in tropical waters. It also discusses the management of injuries caused by dangerous marine creatures.