A dad did what any panicked parent would — he dove straight into the Atlantic after his young daughter fell off a Disney cruise ship — and the wild rescue played out in real time via passengers’ phones.

It all went down around 11 AM Sunday — when a little girl, about 5 years old, fell overboard from the 4th deck of the $900M Disney Dream as it cruised back to Fort Lauderdale from the Bahamas … and without missing a beat, her dad jumped in right after her and rescued her.

The two were left treading rough waters for a nerve-shredding 20 minutes until they were rescued by boat staff.

It’s still a mystery how the girl fell overboard — especially with plexiglass safety barriers in place.