There are 718 islands and islets, 289 rocks and 78 reefs along the Croatian coastline and that is why Croatia is known as the country of 1000 islands. Average depth of Adriatic Sea is about 173 metres Adriatic sea is much deaper on the South than on the North. For example, the highest depth of the sea in Istria is 50 m, while at istand of Palagruža it reaches up to 250 m and around the most distant island of Jabuka it even reaches 1,300 m in depth. The sea current flows along the Croatian coastline in a northwesterly direction. Salinity in the south Adriatic is 38%, which is higher than the world average. Also clarity of the sea goes from around 20 metres in the north to 50 metres in the south Tides are higher in the north (up to about 1 meter) than in the south.