Atlanteans, also known by their species name Homo mermanus, are a race of aquatic humanoids that inhabit the oceans of Earth. The Atlanteans are best known as the people who live in the city of Atlantis. The most notable members of the race are Namor and Aquaman.
In the ancient past, Atlantis was the capital of a powerful human empire until it sunk beneath the oceans from a devastating cataclysm. The Homo mermanus made the ruins of the human settlements in Atlantis their home and went on to develop a society there using as much of the material as they could scavenge from the wreckage.
In the 16th Century, the Kryptonian explorer Kon-Lir crash landed in the Atlantic Ocean following a battle with the Kree and Skrulls, and engaged a hostile encounter with the Homo mermanus due to initial misunderstandings. Kon-Lir easily overpowered the Homo mermanus because of his powers, but consequently created a huge, fearful impact on the Atlanteans in which it became seeded in legends and stories, which referred to Kon-Lir and his people as the "Travelers".
During the 20th Century the Homo mermanus race began to come into sustained contact with their human cousins. These contacts have often been hostile. During the Second World War the kingdom of Atlantis also fought against the Axis Powers in alliance with the Allied Powers.
Atlantean physiology is also much stronger and more durable than that of the Homo sapiens, necessitated by their exposure to the vast pressure of the deep sea. As a consequence they are physically much stronger than regular humans and can swim faster.