Aquaman's first origin story was presented in flashback from his debut, narrated by the character himself:
|The story must start with my father, a famous undersea explorer — if I spoke his name, you would recognize it. My mother died when I was a baby, and he turned to his work of solving the ocean's secrets. His greatest discovery was an ancient city, in the depths where no other diver had ever penetrated. My father believed it was the lost kingdom of Atlantis. He made himself a water-tight home in one of the palaces and lived there, studying the records and devices of the race's marvelous wisdom. From the books and records, he learned ways of teaching me to live under the ocean, drawing oxygen from the water and using all the power of the sea to make me wonderfully strong and swift. By training and a hundred scientific secrets, I became what you see — a human being who lives and thrives under the water.|
In his early Golden Age appearances, Aquaman could breathe underwater with gills, had superhuman strength enabling him to swim at high speeds, and could communicate with sea life and have them do his bidding. Initially, he was depicted as speaking to sea creatures "in their own language" rather than telepathically, and only when they were close enough to hear him. While he was often described as the "sovereign of the sea," with the waters of the entire globe his "domain," and almost every sea creature his "loyal subject," the title was never an official one. Aquaman's adventures took place all across the world, and his base was "an ancient temple of lost Atlantis, kept underwater," in which he kept a solitary throne.
During his wartime adventures, most of Aquaman's foes were Nazi U-boat commanders and various Axis villains. The rest of his adventures in the 1940s and 1950s had him dealing with various sea-based criminals, including modern-day pirates such as his longtime archenemy Black Jack, as well as various threats to aquatic life, shipping lanes, and sailors.
Starting in 1959, Aquaman's backstory was revised, with various new supporting characters added and several adjustments made to the character, his origins, his powers, and persona.
In Adventure Comics #260 (May 1959) and subsequent Silver Age comics, it was revealed that Aquaman was Arthur Curry, the son of Tom Curry, a lighthouse keeper, and Atlanna, a water-breathing outcast from the lost, underwater city of Atlantis. Due to his heritage, Aquaman discovered as a youth that he possessed various superhuman abilities, including the powers of surviving underwater, communication with sea life, and tremendous swimming prowess. Eventually, Arthur decided to use his talents to become the defender of the Earth's oceans. It was later revealed that he had, in his youth, adventured as Aquaboy and met Superboy (Earth's only other publicly active superpowered hero at the time) on one occasion. When Arthur grew up, he called himself "Aquaman".
It was later revealed that after Atlanna's death, Tom Curry met and married an ordinary human woman and had a son named Orm Curry, Aquaman's half-brother. Orm grew up as a troubled youth in the shadow of his brother, who constantly bailed him out of trouble with the law. He grew to hate Aquaman not only for the powers that he could never possess but also because he believed that their father would always favor Aquaman. Orm disappeared after becoming an amnesiac and would resurface years later as Aquaman's archnemesis,Ocean Master.
Aquaman's ability to talk with fish eventually expanded to full-fledged telepathic communication with sea creatures even from great distances and he was also retroactively developed a specific weakness akin to Superman's vulnerability to kryptonite or Green Lantern's vulnerability to the color yellow: Aquaman had to come into contact with water at least once per hour, or he would die (prior to this story Aquaman could exist both in and out of water indefinitely