Mirages seen at sea have a long history of being interpreted as distant islands and mythological realms. Hot and cool pockets of air refracting light can make boats and islands appear as if floating in air. These atmospheric visions can be studied as physical phenomena and as cultural imaginaries, an extension of what Philip Hayward has called the aquapelagic imaginary. In alliance with Donna Haraway’s mythology-inspired Chthulucene, this article will use the Chinese folklore of the shen (‘clam-monster’) to consider ecological issues around deep sea mining. In the ancient etiology of the shen, its breath was thought responsible for visions of Penglai, the fabled island home to the Eight Immortals believed to lie somewhere in the Yellow Sea. The search for Penglai and its rumored elixir of life has now been supplanted by exploration for methane, a largely untapped fossil fuel seeping up from the ocean floor. The clams and multi-species communities that cluster around these emissions, alongside mythological sea creatures, give shape to changing affects and atmospheres on the horizon.