Seeker of Secrets
How many marvels are lost to us simply because they lie sleeping under the salty veil of the ocean depths? Forgotten civilizations, fantastical undiscovered species, lightly napping eldritch horrors? A simple submarine trek could reveal worlds of ancient art and cultures. A delightful prelude, quickly sundered by the nightmare of awakening elder gods with that clunky sub. Leviathans will rise. Reality will sunder, cities will crash to smouldering rubble, and madness will strangle the minds of the unlucky survivors. The slaves who serve these new masters will ask why we foolhardily embraced curiosity, and "discovery" will be the most savage curse word. Mankind will live out the rest of eternity in misery and terror, and we will be to blame for prodding the icy depths we do not understand.
Or maybe we'd find super cool mermaid cities or something! Maybe they have awesome sushi restaurants and their own Cirque Du Soliel shows! The tourism industry would boom, and a bright future of sharing culture and technology would bring us into a new age of enlightenment!
But definitely only one of those two things.
Worth the risk. Let's build some more submarines already!