line of sight
line of vision

Most cannot be seen from line of sight, since they are under water.

Well, the only thing to do was not to be in line of sight.

They have much better sight lines, so you can see.

It would be the only place with a really good line of sight.

From her line of sight she could make out the kitchen.

"Stand away from him and give me a clear line of sight."

These are used when a straight line of sight isn't possible.

But the other two from below were in line of sight.

Especially not when you were in his direct line of sight.

A direct line of sight to the south is necessary, he said.