Notes: Aquaman of Earth-Two is distinctly different from the Aquaman of Earth-One in a few key areas. This Aquaman has no ties to Atlantis royalty, instead he gained his powers from a series of experiments by his parents, a marine-biologist and an oceanographer. This Aquaman can breathe under water and talk with marine life, but for the most part that was about it. His adventures were mostly to educate regarding the mysteries of the depth.
This Aquaman never really became a true heroic figure staying to research and avoiding exploits with the All-Star Squadron or the Justice Society of America.
As it is commonly accepted that there is no Earth-2 counterpart to Topo, it can be inferred (but not definitively confirmed) that Topo's first appearance coincides with the first appearance of the Aquaman of Earth-1, making the Earth-2 Aquaman's possible final appearance Adventure Comics (1938) #228.