Could it be translated to, "How many meters deep is this river"?
in English probably "how deep is this river" would sound better
Your translation would be correct without 'meter' being included. Also, as the course uses English (not US English) meter should be translated to metre.
It's not an accurate translation though. The speaker is specifically asking the answer to be given in metres, right?
"How deep is this river in meters" would be ok