Neretva Science Week 2023 took place from May 30th to June 7th. A diverse team of 62 scientists from 17 countries gathered in small town Ulog, to contribute to the conservation of the Neretva river system. Here, we gathered the preliminary results of Neretva Science Week 2023, covering 19 studies or fields of expertise. They reflect the enthusiasm of involved scientists as well as convey an impression of the extraordinary value of the Upper Neretva River and Valley.