Add all ingredients except seltzer to a cocktail shaker with crushed ice and 4-6 whole ice cubes, shake, open pour into an empty young coconut shell or Tiki mug. Top with seltzer.
Recipe from: Cate, Rebecca and Martin Cate. "Monk's Respite." Smuggler's Cove: Exotic Cocktails, Rum and the Cult of Tiki. Ten Speed Press, 2016.