"there" is pronoun or adverb?

[aaronhee]

Hi All,

I would like to understand more about the part of speech is the word "there". According to Oxford Dictionary, there is describe as an adverb as in the sentence:

'There is a glass."

where "there" is the adverb to the verb "is".

However, often than not, we heard the sentence:

"We are going in there".

I find this sentence seemed ungrammatical as that would indicate that "there" acting as a pronoun for a place that is mentioned before. For example,

"This is the cave. We are going in there."

Even then, I would think that the word "there" redundant, it should be just:

"This is the cave. We are going in."

So I would appreciate if anyone can enlightened me on the correct usage of this word in the above cases.

Thank you.

[engee30]

Just on one simple example, I'm going to show you the difference:

There is a glass there. where the first there is a pronoun (the so-called existential there) and the other there is an adverb.