The Warta Mouth National Park (Polish: Park Narodowy Ujście Warty) is the newest of Poland's 23 national parks. It was established on June 19, 2001, in the area of the lowest part of the Warta River, where it meets the Odra (Oder) River. This meeting point is the border between Poland and Germany. The park covers an area of 80.38 square kilometers (31.03 square miles) within the Lubusz Voivodeship.

The park was created on the site of the former Słońsk Nature Reserve, which had been protected since 1977, and parts of the Ujście Warty Landscape Park. The land here is wet and muddy, making it a home for many bird species. Because of this, the former Słońsk reserve, now part of the park, was added to the Ramsar Convention in 1984. This international agreement helps protect wetland areas like this one.

The park’s headquarters is located in the village of Chyrzyno, close to the town of Kostrzyn nad Odrą.

Waters

The park's main river is the Warta, which divides the park into two areas: the Southern part (including the former Słońsk reserve) and the Northern part, known as the Northern Polder. In the Southern area, water levels can change by up to four meters each year, and the park here acts as a large seasonal lake to hold extra water. Water levels usually rise in late fall but are highest during spring, from March to April. The Northern part has many canals and is separated from the Warta River by a levee.

Wildlife

Plant life in the area is very different in many ways. Most of it is natural, but human activity has changed it a lot, especially in the forested areas. However, the wetlands near the Warta River have remained mostly untouched. These areas are important for scientists from Poland and other European countries to study because many major rivers in Europe have been changed by people.

This park is one of the most important places in Poland for bird nests. There are 245 bird species here, including nests for 160 types, such as 7–8 kinds of ducks. Twenty-six of these bird species are endangered, according to BirdLife International. These include Acrocephalus paludicola, Crex crex, Limosa limosa, Grus grus, Botaurus stellaris, Ixobrychus minutus, and Chlidonias niger.

The park also has 34 types of mammals, such as otters (Lutra lutra) and beavers (Castor fibre).

A major problem for the park’s ecosystem is the return of large plants to the meadows and pastures. These plants can harm bird nests, so the park’s leaders have taken steps to control their growth.

Since May 31, 1996, there has been a Natural Education Center in Chyrzno. Since the fall of that year, the center has offered classes for students and young learners. Activities include trips to the park, bird-watching camps, and ecology lessons. The park has walking and cycling paths, as well as two nature trails called “Ptasim szlakiem” (“Along birds’ trail”), which go through the most valuable parts of the Słońsk reserve.

The park’s Board owns a small lodge with five rooms that can sleep 15 people and a guest house for about 30 visitors.