The exact extent of undiscovered areas in the ocean is difficult to determine with precision. it is estimated that approximately 80% of the world's ocean remains unexplored or inadequately mapped. This estimation takes into account the vastness and depth of the oceans, as well as the technological limitations that have hindered comprehensive exploration.
The majority of the unexplored areas lie in the deep ocean, particularly in the depths below 200 meters (656 feet) known as the mesopelagic, bathypelagic, abyssopelagic, and hadal zones. These regions are characterized by extreme pressure, low temperatures, and limited access, which pose significant challenges to exploration efforts.
Since my knowledge is not up-to-date, there may have been some advancements in ocean exploration and mapping beyond my cutoff date. It is advisable to consult more recent sources or scientific publications for the most accurate and current information on the topic.