Briny deep and Seven seas

Seven seas and briny deep are semantically related in very large body of water topic. In some cases you can use "Seven seas" instead a noun phrase "Briny deep", when it comes to topics like open ocean.

Seven seas noun - The whole body of salt water that covers nearly three-fourths of the earth.

Briny deep and seven seas are semantically related in open ocean topic. You can use "Briny deep" instead a noun phrase "Seven seas".