There isn't a single perfect antonym for "hydrosphere" because it refers to the entire body of water on Earth. However, depending on the context, you could use these terms:

* Lithosphere: This refers to the Earth's solid, rocky outer layer. It is the opposite of the hydrosphere in terms of physical state.

* Atmosphere: This is the layer of gas surrounding the Earth. While it interacts with the hydrosphere, it's a separate component.

* Biosphere: This encompasses all living things on Earth. While the biosphere depends on the hydrosphere, it's not directly opposite.

* Land: This is a more general term that refers to the solid, non-watery part of the Earth's surface.

The most appropriate antonym depends on the specific context of your use.