1. Tomorrow, we're going to go to hike.

Question

2. Tomorrow, we're going to go hiking.
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Which one is grammatical? Are both grammatical? Then, what is the differencein meaning?

Answer 1

Both are grammatically correct. When we say we are going to "go to" it usually means a destination, to a park, to the store, to a restaurant, whatever. It's not usual to consider a hike a destination. We would say #2. It means or implies that the hiking is the "going", as in movement, not the destination.

Answer 2

Agreed, "go to" is not associated with a verb but usually a noun. Try reading the sentence out loud if it sounds weird it usually is.

Answer 3

1. Tomorrow, we're going to go to hike.
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Does this sentence mean the following sentence?

3. Tomorrow, we're going to go so that we may hike.