quote from Wikipedia:
The Vistula (Polish: Wisła; German: Weichsel; Czech: Visla ), is the longest river in Poland at 1,047 km (678 miles) in length. It drains an area of 194,424 km² (75,067 sq. miles), of which 168,699 km² (65,135 sq. miles) lies within Poland (over half the area of the country).
The Vistula has its source in the south of the country, at Barania Góra (1220 m high) in the Silesian Beskids (western part of Carpathian Mountains) where it starts with the White Little Vistula (Biała Wisełka) and the Black Little Vistula (Czarna Wisełka). It then continues to flow over the vast Polish plains, passing several large Polish cities along its way, including Cracow, Sandomierz, Warsaw, Płock, Włocławek, Toruń, Bydgoszcz, Świecie, Grudziądz, Tczew and Gdańsk. With a delta and several branches (Leniwka, Przekop, Śmiała Wisła, Martwa Wisła, Nogat and Szkarpawa) it empties into the Vistula Lagoon, or directly into the Gdańsk Bay of the Baltic Sea.
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Very, very close to the Old Town Main Market you can see this panoramic of Vistula river (Wisla, as we call it in Polish). On the other shore you'll see Praga, the right-hand part of Warsaw.
I especially love the greens here.
Getting out and about is a must and one of the easiest ways to see a bit of Warsaw that isn't in the guidebooks is to set off on a wander along the banks of the river. There is only a relatively small stretch of the banks - on the western bank below the Old Town and a little south - which has been 'developed'. On the eastern side of the river you can wander between the trees and onto the sand banks and jetties where the fishermen ply their trade. Head a little further south to Siekierki bridge and you will get the most stunning panoramas of the Warsaw cityscape imaginable.
If you have the chance get out and about a bit, escape the Warsaw rush with a trip to Lake Zegrze. It's about forty kilometres north east and is a great destination in winter when the snowbound landscape comes alive with the buzz of single engine iceplanes. Summer is even better and you can go off and explore some of the landing stages on hidden lakes. If you're sharp-eyed enough you'll catch a kingfisher whizzing by, or a treecreeper snaking its way up and down the trunk of a tree.
The river makes an amazing site in winter when it is sometimes frozen. In summer, you may be able to bungee jump over the river.