There are multiple ways to maintain suspense. Withholding information is one technique, but sometimes you can actually build more suspense by telling the reader more instead of less. Blatant surprises your reader didn’t see coming can backfire when they find them irritating.
You can still keep the reader wondering what will happen by giving them more information. If the reader knows what’s going on behind the scenes and that the protagonist is in danger, they’ll be biting their nails, wanting to warn them, and wondering how the hero or heroine will handle it.
One way to think about this is to consider whether stories about the Titanic are any less suspenseful for knowing how it ends?