Boulder choke

A boulder choke is a collection of large rocks or rubble that obstructs a shaft or passage in a cave or mine.

In order to progress through passages cavers often need to negotiate or clear boulder chokes.

[1] In order to clear a boulder choke the rocks obstructing the passage may need to be removed, often requiring breaking up first either mechanically or using a small explosive.

[5] In caves prone to flooding, a narrow and contorted path through a boulder choke can fill up with water quickly, preventing progress.

[6] In 1972, ten members of the University of Leeds Speleological Association were trapped behind a complex flooded boulder choke in Langcliffe Pot, resulting in a 44-hour-long trip.