Focusing on Vegetation:
* Forest: A dense area of trees, the opposite of the open, grassy nature of a savanna.
* Jungle: A dense, tropical forest, emphasizing the lack of openness and the abundance of vegetation.
* Tundra: A treeless, cold environment with low-lying vegetation, contrasting the warm, grassy savanna.
Focusing on Geography:
* Desert: A dry, barren area with little vegetation, contrasting the savanna's moderate rainfall and grassy plains.
* Mountain: A high, rocky elevation, contrasting the savanna's relatively flat terrain.
* Arctic: A cold, icy region with little vegetation, emphasizing the difference in climate and vegetation.
Focusing on Ecosystem:
* Temperate Forest: A forest with a moderate climate and diverse tree species, emphasizing the difference in climate and vegetation.
* Wetlands: An area with waterlogged soil and diverse aquatic life, emphasizing the difference in moisture levels and habitat.
* Ocean: A vast body of water, highlighting the contrast between land-based savanna and marine ecosystems.
The best antonym for "savanna" depends on the specific context and what you want to emphasize.