In the Argonautic expedition, after the death of Tiphys, helmsman of the "Argo," he took his place.
He destroyed sundry sea-monsters, set free the bound Prometheus, took part in the Argonautic voyage and the Calydonian boar hunt, made war against Augeas, and against Nestor and the Pylians, and restored Tyndareus to the sovereignty of Lacedaemon.
Autolycus is also said to have instructed Heracles in the art of wrestling, and to have taken part in the Argonautic expedition.
He was a great friend of Jason, and took part in the Calydonian boar-hunt and the Argonautic expedition.
Acastus was represented with his famous horses in the painting of the Argonautic expedition by Micon in the temple of the Dioscuri at Athens.