Answer:
discovered 5 percent
Step-by-step explanation:
Despite its size and impact on the lives of every organism on Earth, the ocean remains a mystery. More than 80 percent of the ocean has never been mapped, explored, or even seen by humans. A far greater percentage of the surfaces of the moon and the planet Mars have been mapped and studied than our own ocean floor has.
According to the National Ocean Service, it's a shockingly small percentage. Just 5 percent of Earth's oceans have been explored and charted – especially the ocean below the surface. The rest remains mostly undiscovered and unseen by humans.