Around 1311 CE, the mansa (sultan) of the Mali Empire sent hundreds of ships to find the other side of the Atlantic Ocean. They were lost at sea, so on the next expedition he sailed into the Atlantic himself. He was never seen again.
Abu Bakr II was the mansa (variously translated as the sultan, king, or emperor) of the Mali Empire in the 14th century. What little we know of his life comes from an account by his successor, the famous Mansa Musa.
Apparently, he was a bit obsessed with finding the end of the Atlantic Ocean. So much so that he sent a fleet out, equipped with several years’ worth of supplies and the instruction to not stop until they got to the other side.
One ship returned. The captain claimed to have fled a whirlpool that had swallowed the rest of the fleet. The mansa prepared a second fleet, appointed a regent (Musa), and left at its head. He was never heard of again.
A few people have kicked around the theory that he actually managed to cross the Atlantic, but no concrete proof has ever been found.