In 1997, researchers recorded the loudest sound ever heard underwater.br br It was called The Bloop — a deep, powerful sound that echoed across the Pacific Ocean... but no known creature or machine could’ve made it.br br Some say it came from a massive iceberg. Others believe it was something still undiscovered… or perhaps not from this world at all.br br What do you think made The Bloop?br br 🔔 Subscribe for more real, mysterious facts every week.