The Bezdna (Russian: Бездна) or Pasna (Chuvash: Пасна) is a river in Chuvashia, Russian Federation, a right-bank tributary of the Sura.

It is 106 kilometres (66 mi) long, and has a drainage basin of 1,320 square kilometres (510 sq mi).

[1] Major tributaries are Abamza, Orbezdna, Black Bezdna.

Average sediment in mouth per year is 71 mm.

In the upper stream use to dry.