Question

Which river is most closely associated with Hinduism

Answer 1

One river that is  famous for being a Holy River in Hinduism is Ganges (or Ganga, as it's also called).

There is a religious ritual in Hinduism to bathe in this river, which in the recent years has caused the river to be very polluted.

 Additionally, it is a major burial site in Hinduism:  people cremate their relatives' bodies on wooden pyres on the river.