Final answer:
The reference to the old sailor who had sailed the Spanish Main suggests he has experienced significant adventures and is about to share his tales or wisdom from his time at sea.
Step-by-step explanation:
When the poem refers to the old sailor who had sailed the Spanish Main, this indicates that the sailor has experienced adventures on the high seas, particularly in the Caribbean, which was known for its piracy and colonial activity during the Age of Exploration. The phrase "Spanish Main" refers to the mainland coast of the Spanish Empire in the Americas and the Caribbean Sea during the 16th to 18th centuries, a time when these waters were frequently traversed by treasure-laden Spanish galleons and thus attracted pirates and privateers. The reference to the old sailor speaking up suggests he is about to share stories or wisdom derived from his extensive experience at sea, likely tales of adventure or danger.