According to Martin Cate, owner of Smuggler’s Cove in San Francisco, when “Trader Vic” Bergeron first published the Martinique Swizzle recipe, the Martinique rum available in the U.S. at the time was largely rich and dark, and made from molasses (unlike the cane-based rhum agricole we find now). Use a rich demerara rum or a dark Jamaican rum such as Hamilton—or, Cate says, take the name literally and use an aged Martinique rhum agricole.