Heracles set out on his expedition, and while crossing the Libyan desert, found the heat unbearable, so much so that in his anger he shot an arrow toward the sun. Helios the sun god (in some versions it was Apollo) pleaded with Heracles to shoot no more. With this request the hero promised he would stop, if he could lend the golden goblet which Helios used to sail across the ocean every evening on his journey home to the east. Heracles was granted his request. The hero sailed across the ocean in the golden goblet to the island of Erytheia. On his journey to Erytheia (in some versions) Heracles set up two landmarks when he reached the straits of Gades, which became known as the "Pillars of Heracles", (but in other versions) he built the pillars to celebrate his journey home.
When Heracles reached Erytheia, no sooner had he landed he was confronted by the two-headed dog Orthrus, with one huge blow from his olive-wood club Heracles killed the watch-dog. Eurythion the herdsman came to assist Orthrus, but Heracles overcame the attack in the same manner. On hearing the commotion Geryon sprang into action, carrying three shields, three spears and wearing three helmets and three sets of greaves. Heracles strung his bow, killing the monster with his deadly arrows. (in other versions Heracles tore Geryon into three separate pieces).
The hero's return journey was not without incident. Herding the cattle on to the golden goblet he sailed back to Greece. However, the hero landed in Italy, and it was here that Cacus, the fire-breathing giant, took a portion of the herd while the hero slept. Cacus dragged the animals backwards into his cave, as to leave no trail for Heracles to follow. On waking and finding part of the herd missing, Heracles searched for them, but was deceived by the trick. Giving them up for lost Heracles drove the rest of the herd past the cave. The cattle inside the cave could hear the herd pass by, and they called back to each other. When Heracles looked inside he saw the cattle, and then came face to face with Cacus. Angered by the giant's trick and the theft of his cattle, Heracles killed him.
Heracles found it hard to keep the herd together, and to make matters worse Hera sent a gadfly (a type of biting horsefly) which scattered the herd with its irritating bite. After regaining control of the cattle, Hera sent a flood, which made crossing a river impossible. Heracles filled the channel with stones which made the water shallow enough to cross. The hero dealt with another monster, which was half-woman and half-serpent as he drove the cattle through Scythia, on his journey home to Greece.
After many hardships Heracles finally reached the court of Eurystheus. The ungrateful king sacrificed the cattle to Hera. It was a rich sacrifice to give to a thankless goddess, as Hera always tried to make the tasks harder for Heracles. Some legends state that this should have been the last labor for the hero but Eurystheus refused to accept two of them, as the Hydra was killed with the help of Iolaus, and for the cleaning of the Augean stables, he used the force of two rivers to accomplish the task. Instead of being thankful for the heroic deeds, the weak and narrow-minded king forced Heracles to undergo two more labors.