What is the fine-grained topic of the following text: The Water Group comprising of Austria, Bahamas, Bosnia & Herzegovina, Brazil, Cambodia, China, Croatia, Cyprus, Ecuador, Egypt, Guadeloupe, Guatemala, Guyana, Indonesia, Israel, Italy, Liberia, Malta, Mexico, New Zealand, Northern Ireland, Paraguay, Puerto Rico, Reunion Island, Serbia, Sri Lanka, Tonga, Ukraine and Vietnam will also participate in the competition tonight. Only return the topic.
Participation of various countries in a competition