Preheat oven to 350 degrees. Spread almonds on a baking sheet and toast, tossing occasionally, until golden, 8 to 10 minutes. Let cool completely.
Bring sugar and 2 tablespoons water to a boil in a saucepan, stirring until sugar is dissolved. Continue to cook, without stirring, until a thermometer registers 235 degrees, about 3 minutes.
Add almonds; cook, stirring, until sugar begins to crystallize, about 1 minute. Stir in salt. Continue to cook, stirring, until a sandlike coating forms on nuts, about 1 minute more. Stir in coconut. Pour onto a parchment-lined baking sheet; let cool 30 minutes.
Transfer nut mixture to a bowl. Add chocolate, stirring to coat. Return to sheet; separate into clusters with a fork. Refrigerate at least 30 minutes and up to 2 days. Before serving, toss with cocoa powder, tapping off excess.