Short answers, pulled from the story.
The Vistula is 1,047 kilometres long, making it the longest river in Poland and the longest river draining into the Baltic Sea. It rises at Barania Góra in the Silesian Beskids, 1,220 metres above sea level, from two sources called the White Little Vistula and the Black Little Vistula.
The name Vistula first appears in writing in AD 40, in the work of the Roman geographer Pomponius Mela. Pliny recorded it as Vistla in his Natural History in AD 77, and Ptolemy used the Greek spelling Ouistoula in the second century AD.
The Vistula was Poland's primary grain trade route for centuries. Tonnage shipped along the river grew from around 14,000 tonnes in 1491 to around 310,000 tonnes at the trade's peak in 1618. Most grain left Poland through Gdańsk, where merchants controlled roughly 80% of the inland river trade and around 70% of the city's exports were grain.
In July 1997, heavy rainfall over the upper Vistula catchment caused what became known as the Millennium Flood, one of the largest floods in modern Polish history. Peak flows exceeded all previously recorded levels, and approximately 1,100 kilometres of flood embankments were damaged or destroyed, exposing structural weaknesses in levees and inadequate flood retention capacity in the basin's reservoirs.
The Oder-Vistula Flood Management Project was a large-scale flood protection programme formally launched in 2015 with an estimated budget of 1.2 billion euros. It was financed by the World Bank, the Council of Europe Development Bank, the EU Cohesion Fund, and the Polish state budget, and was designed to protect an estimated 15 million people, including around 122,000 living in areas at risk of a one-in-100 year flood.
The Vistulian glaciation, also called the Weichselian glaciation, is the name given to the most recent glacial period in northern Europe, which occurred approximately between 100,000 and 10,000 BC. It is named after the Vistula because the river's basin was significantly shaped by the advance and retreat of the ice sheet during this period.