DC Comics Presents #5 — “Superman and Aquaman: The War of the Undersea Cities!”

DC Comics Presents #5 (January 1979) features a two-part team-up between Superman and Aquaman to prevent a war between the undersea cities of Tritonis and Poseidonis 

Plot Summary

On the beaches of Metropolis, an old fisherman pulls up a mermaid named Lori Lemaris from the sea. Intrigued by the fame and fortune she could bring, he quickly realizes she’s searching for Superman — and that she’s in trouble. Lori is taken to S.T.A.R. Labs, where Superman is surprised to hear from his long-lost girlfriend. She warns him that Tritonis, her home, has been attacked by a war party from Poseidonis, seemingly led by Aquaman