There's a turn ahead and then the floor opens into a chamber with a river running through.

She opened the door into a chamber warm with candlelight.

Ten meters within, it opened into a great chamber in the heart of the mountain.

It opened into a vast chamber, or a set of chambers, like a dark museum.

It opened into a large chamber whose floor was a level below them.

Then it opened into a chamber where a collection of junk lay.

The passage opened into a larger chamber ten feet farther down.

The door opened into a great chamber whose ceiling rose to the full height of the keep.

The tunnel was short and opened into a larger chamber.

At one point the river opened into a large chamber with an air pocket.