圧倒的な情報量に驚きましたって英語でなんて言うの？

To express that one is surprised by something you may make use of the following words;
taken aback, bewildered or to be amazed by.
Taken aback by something. To be taken aback means to be surprised by something. You may say that you were bewildered or that it wasn't as expected. These expressions all show an element of surprise.

These sentences above state that someone is very surprised with the fact that said website has so much information.

If something or someone is 'a mine of information' then it means, here you can find a wealth of data which is useful.

A "pleasant surprise" is a way to say that you were surprised but in a good way. It lets your listener know that you are happy that there was so much information on the website.

I hope that this helps :)

When we are presented with too much information at one time it can be overwhelming.
We don't usually like to go through huge amounts of work in short spaces of time.
'too much'expresses that it is over and above what was expected.

Shocked - another word for surprised.
Info - the abbreviated term for information.
"To take in" - means to absorb/to understand

The literal translation of this expression is "I was surprised at the overwhelming amount of information." This is a grammatically accurate translation of this sentence. Therefore, you may use it. There are also a number of different ways you could say this expression as well. You could say:

1. I was surprised by how much information was on the website.
2. I was overwhelmed by the amount of information on the page.

3. I was shocked by all of the information on the website.

   There are any number of words you could use for this expression such as:

4. taken aback
5. overwhelmed
6. shocked

7. surprised

   Likewise, you could use words such as website or web page, or simply page if you wanted to.

   There is not just 1 correct way to say this sentence. There are any number of ways you could translate this, and still be both grammatically correct, and sound natural at the same time.

When you want to express to a person that you were surprised to find a lot of information on a certain website (on a particular subject); then you may express this in the following ways:
-I was surprised by how much information there was on the website
-I was shocked to find out that the website had a lot of information (about dogs)