The least explored ocean is the Southern Ocean (also known as Antarctic Ocean, Austral Ocean). This is due to the very strong and cold winds and storms, that cause very big waves, so the exploration is taken down to the minimum because the circumstances are way to risky for the lives of the explorers. On top that, there's also lots of icebergs moving from Antarctica to the north through out the whole year, in big portion of the ocean, which makes exploration even harder and riskier.
