A terrestrial environment is a land-based habitat, such as a forest, grassland, or desert, while an aquatic environment is a water-based habitat, such as an ocean, river, lake, or pond.

The pair 'Forest and Ocean' correctly represents a terrestrial environment (forest) followed by an aquatic environment (ocean), matching the order asked in the question.

Lake and River are both aquatic, Pond and Grassland reverse the required order (aquatic then terrestrial), and River and Desert also reverse the order (aquatic then terrestrial), so none of these fit the terrestrial-then-aquatic sequence correctly.

Therefore, the correct answer is Forest and Ocean.