Final answer:
The participial phrase in the given sentence is 'After sailing around the world,' which acts as an adjective, providing context to the main action by describing the voyager's activity prior to the sinking of the boat and his subsequent return home.
Step-by-step explanation:
In the sentence 'After sailing around the world, his boat sank, and, the voyager returned home, leaving adventure behind,' the participial phrase is 'After sailing around the world.' This phrase contains the participle 'sailing,' which describes the action the voyager was engaged in before the events described in the rest of the sentence. Participial phrases can function as adjectives, providing details and descriptions in relation to the noun they modify. In this case, the participial phrase modifies 'his boat,' and provides background to the action that follows in the main clause.
Participial phrases like this one are often used to add context or extra information to the main clause of a sentence, helping to create a more vivid picture of the scenario for the reader.