The term 'Briny Deep' is a phrase used to describe the depths of the SEA. The crossword solutions for this term are SEA (3 letters), OCEAN (5 letters), and BOUNDINGMAIN (12 letters). SEA refers to a large body of salt water, while OCEAN is the largest body of water on Earth. BOUNDINGMAIN is an archaic term used to refer to the OCEAN, typically in a poetic or romantic context. Together, these three words provide a vivid description of the vastness and beauty of the SEA.