The third Sunday in May of each year is the International Day of the Baltic Harbour Porpoise (IDBHP). It was introduced 20 years ago by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (UNEP/ASCOBANS). IDBHP aims to raise awareness on the critical conservation status of the only cetacean species population native to the Baltic Sea.