River tourism is exceptionally popular among the Czech people, who sail by canoes, rafts or other boats downstream major Bohemian rivers as Vltava, Sázava or Lužnice. The most popular and frequented river section is the Vltava from Vyšší Brod via Český Krumlov to Boršov nad Vltavou, which is visited by as many as hundreds of thousands paddlers (in Czech called "vodáci", sg. "vodák") a year. In peak season, "traffic jams" can be regularly seen on the busiest rivers, mainly at weirs. There has even some "paddlers' culture" developed, with peculiar slang, songs, traditions etc., related to the Czech tramping movement.