Frank R. Paul's Deep-Sea Monster Encounter, Amazing Stories 1927

Startlingly visceral for a 1927 pulp interior, this pen-and-ink nightmare depicts a deep-sea diver in antiquated hard-hat diving gear squaring off against a colossal, cyclopean sea creature with a spiraling, barnacled eye and wing-like membranous fins — rendered in stark white-on-black line work that feels more like a fever dream than scientific illustration. Alien flora and egg-like formations crowd the ocean floor as the lone figure lunges forward with a tool or weapon, dwarfed by the leviathan.