Locks and weirs on the River Thames
The English River Thames is navigable from Cricklade (for very small, shallow boats) or Lechlade (for larger boats) to the sea, and this part of the river falls 71 meters (234 feet). There are 45 locks on the river, each with one or more adjacent weirs.
Source: Wikipedia — Locks and weirs on the River Thames (CC BY-SA 4.0)