"Thais" - Society for Exploration and Conservation of Nature is nonprofit, nongovernmental and nonpolitical public organization. It was founded in 1997 as a successor of student's Underwater Research Group - "Thais" which previously worked within the Croatian Biological Society. Members are mostly biology students from University of Zagreb, one from Basel, Switzerland and one from Hawaii. During last three years we performed a project "The macrobenthos survey along the coasts of Mljet national park " under the professional guidance of three experts in marine biology (Ph. D. Dušan Zavodnik, Ph. D. Elvis Zahtila and prof. Jelena Belamarić). We also held 20 lectures, published several papers and articles and organized several ecological actions through which we tried to influence people attitudes about nature and it's conservation.