Atlas was punished by the Olympian gods to carry the Heavens upon his shoulders
Family of Atlas
Atlas was the son of the Titan Iapetus and the Oceanid Clymene and brother of Prometheus, Epimetheus and Menoetius. He was married to the titaness Pleione who bore the seven sea deities with the name Pleiades ("the sailing") and special Nymphs with the name "Hesperides", also known as the "Daughters of Evening".
The Punishment of Atlas
Contrary to his brothers, Atlas sided with the Titans during their War with the Olympian Gods and acted as their leader, threatening the Olympians constantly. However, the Olympian Gods managed to dethrone the Titans and cast all titans into Tartarus, the depths of the Underworld. Only Atlas became singled out and received the harshest punishment by King Zeus: he was doomed to hold up the heavens with bare hands and bear their weight on his shoulders forever. This way, Atlas became the first to know that the earth was spherical in shape.
Furthermore, Atlas must have had a close relationship to the sea, since he knew all secrets of the sea ground.