Sub-Mariner #23

The cover by Marie Severin and Mike Esposito says it all: a massive, blue-skinned humanoid — Orka — towers over an undersea cityscape, hoisting Namor himself overhead with one enormous hand while armored Atlantean warriors scramble in the background. The bold tagline "How Do You Stop a Human Killer Whale?" perfectly captures the sense of a threat that has Prince Namor, king of the seas, genuinely outmatched. It's a striking 1970 Marvel image that makes this issue hard to pass up.