Important geographic facts
Poland's territory extends across several geographical regions, between latitudes 49° and 55° N, and longitudes 14° and 25° E. In the north-west is the Baltic seacoast, which extends from the Bay of Pomerania to the Gulf of Gdańsk. This coast is marked by several spits, coastal lakes (former bays that have been cut off from the sea), and dunes. The largely straight coastline is indented by the Szczecin Lagoon, the Bay of Puck, and the Vistula Lagoon. The centre and parts of the north lie within the North European Plain.
Rising above these lowlands is a geographical region comprising the four hilly districts of moraines and moraine-dammed lakes formed during and after the Pleistocene ice age. These lake districts are the Pomeranian Lake District, the Greater Polish Lake District, the Kashubian Lake District, and the Masurian Lake District. The Masurian Lake District is the largest of the four and covers much of north-eastern Poland. The lake districts form part of the Baltic Ridge, a series of moraine belts along the southern shore of the Baltic Sea.
Źródło: https://en.wikipedia.org/wiki/Poland#Geography
Where to go in wroclaw?
Ostrów Tumski is the oldest part of the city of Wrocław. It was formerly an island (ostrów in Old Polish) known as the Cathedral Island between the branches of the Oder River, featuring the Wrocław Cathedral built originally in the mid 10th century.
The 13th century Main Market Square (Rynek) prominently displays the Old Town Hall. In the north-west corner of the market square there is the St. Elisabeth's Church (Bazylika Św. Elżbiety) with its 91,46 m tower, which has an observation deck (75 m). North of the church are the Shambles with Monument of Remembrance of Animals for Slaughter (pl). Salt Square (now a flower market) is located at the south-western corner of the market square. Close to the square, between Szewska and Łaciarska streets, there is the St. Mary Magdalene Church (Kościół Św. Marii Magdaleny) established in the 13th century.
Źródło: https://en.wikipedia.org/wiki/Wroc%C5%82aw
Wonderful polish lakes
Masuria and the Masurian Lake District are known in Polish as Kraina Tysiąca Jezior and in German as Land der Tausend Seen, meaning "land of a thousand lakes." These lakes were ground out of the land by glaciers during the Pleistocene ice age around 14,000 - 15,000 years ago, when ice covered northeastern Europe. From that period originates the horn of a reindeer found in the vicinity of Giżycko.96 By 10,000 BC this ice started to melt. Great geological changes took place and even in the last 500 years the maps showing the lagoons and peninsulas on the Baltic Sea have greatly altered in appearance. More than in other parts of northern Poland, such as from Pomerania (from the River Oder to the River Vistula), this continuous stretch of lakes is popular among tourists. The terrain is rather hilly, with connecting lakes, rivers and streams. Forests account for about 30% of the area.9798 The northern part of Masuria is covered mostly by the broadleaved forest, while the southern part is dominated by pine and mixed forests
Źródło: https://en.wikipedia.org/wiki/Masuria#Landscape