Aquaman was born different from other Atlanteans: he could breathe air, withstand sunlight, communicate with sea life, and had blonde, curly hair. As a young adult, he attempted to trap a trapper, but ended up the man's captive. He was let go when he began gasping. Back in the water, he was fine.
The next day, the trapper had two fish on his doorstep. Aquaman was sitting on a rock in the sea watching him. As time went on, the man began to get fed up with him - his traps would have meals in them before he could even place them in the water. He did it not only for food, but for sport. Aquaman was taking the fun away. They eventually became the best of friends, the man even taught him to read, write, and speak. Years later, Aquaman returned from a swim to find his "father" dead. He'd left his journal for the boy to read. He'd been seeing creatures in the sea that he was certain were out to kill his "son." He left the boy his name: Arthur Curry.
He fled and looked for the fabled Atlantis. After experiencing some of the land of the "surface dwellers," he found Atlantis. He was captured and placed in the "aquarium" - an Atlantean prison. He spent three years there in the formal orange and green outfits. There, he met Vulko. The old man helped him learn the language of the underwater kingdom. He saw a woman who he believed to be his mother, but knew later she was dead. He escaped the prison.
Aquaman began a crusade against pollutants, etc. and helped form the original Justice League of America. When he returned to Atlantis, he was a hero. The Aquarium had been turned into a museum. Vulko took their hero to the king. He was granted full citizenship. He later learned that his mother had once been queen; the people demanded he take the throne. Vulko told him that any child born with a deformity was left to die - his mother would have never known he survived.
He eventually found friendship (Aqualad) and a queen: Mera. She was a woman from another dimension who gave him a son, Arthur, III. The child was killed just short of his second birthday and Aquaman abandoned his home and all he held dear.