"Berapa volume air di laut?"

Translation: What is the water volume in the sea?

[Fred_Van]

The English translation is awkward. Better sentences would be: "How much water is in the ocean?" or "What is the volume of water in the ocean?"

[Jspharmando]

Berapa is a question word to ask about quantity (countable or uncountable).
The translation in English is correct “what is ...” not “how much ...”

[Ria___]

My sentence is being corrected to:

You used the wrong word. What's is the volume of water in the sea?

"What's is" is obviously a typing error.

[KrisHoki]

"what is the volume of water in the sea" is better, I couldn't say that the English was unnatural.