Possible Clues:

• Sea of west Atlantic noted for seaweed
• Sea near the West Indies
• A grass spreading, so covers the sea
• Sea in the North Atlantic
• So, a grass makes it a sea of weed
• Mass of weed sees second fool stuck in ship
• Seaweed finally making fool break oars at sea
• Foreign ruler entertains king aboard ship on such a sea?
• The artist's great like this for the sea
• Seaweed-rich sea