Floodgate
From WikiRaider
A Floodgate is a contraption that controls water flow. Such a floodgate can be found in Tomb Raider Anniversary, in the Peru level The Lost Valley.
Upon Lara's arrival the floodgate is open, allowing water to flow down from the river into a pond. Due to that the current in the river will not allow Lara to steer much - it will especially prevent her from getting into an underwater cavern containing one of the Relics, the Kero Mug - and will take her back down into the pond instead.
The main objective of the Lost Valley level is to lower the floodgate, as the entrance to Qualopec's Tomb is hidden behind the stream of water flowing down into the pond.
Closed Floodgate
Entrance to Qualopec's Tomb
