Preheat oven to 350°. Pulse cookies in a food processor until finely chopped. Combine crumbs and melted butter; press onto bottom of a greased, foil-lined 13x9-in. baking pan. Spread coconut over crust; sprinkle with crisp rice cereal., Combine dulce de leche and water until smooth. Pour over cereal. Sprinkle pecans over dulce de leche; press down lightly., Bake until edges are set but center is still soft, about 30 minutes. (Do not overbake.) Remove from oven; immediately sprinkle with sea salt. Cool completely on a wire rack before cutting into 24 squares.