Across Vs Through

 

Typical mistake: It took us 5 hours to walk across the jungle. 

Both across and through can be used for a movement from one side of an area to another. 

Across is related to On - it suggests that the movement is on a surface. 

Through is related to In - you move through a 3-D space, with things on all sicks. 

Compare the following: 

The lake was frozen, so we walked across the ice.

It took us 2 hours to walk through the rice field.

I walked across the square to the cafe. 

I pushed through the crowds to the bar. 

Through is used for a movement from one side to the other of something 'long and thin', like a rive. 

He swam through the river. (Not: ...through the river.)