Across
1
Low-lying land surrounded by higher ground
4
Line dividing two countries
5
Largest river in South America
6
Region between the two tropic lines
9
Raised area of land, smaller than a mountain
11
Region near the equator
Down
2
Height above sea level
3
Land surrounded by water on three sides
7
Deep narrow valley with steep sides
8
Region surrounding the North Pole
10
Largest ocean on Earth