General:
* The floor
* The wooden floor
* The tiled floor
* The carpet
* The surface of the floor
* The flooring
Specific:
* The kitchen floor
* The bedroom floor
* The top floor
* The first floor
* The basement floor
* The dance floor
Figurative:
* The floor of the ocean
* The floor of the canyon
The best noun phrase for you will depend on the context of your sentence.