Captain Obed Marsh was a leading Innsmouth seafarer of the early nineteenth century who, during Pacific voyages, witnessed Polynesian islanders trading with the Deep Ones and learned the nature of their pact. Returning home, he founded the secret Esoteric Order of Dagon.
His bargain brought Innsmouth abundant fish and gold, but the price was interbreeding with the Deep Ones and worship of Dagon and Cthulhu. Across generations Innsmouth fell ever more completely under the law of the deep.