In general, the seven continents we are talking about are Asia, Europe, Africa, Oceania, North America, South America and Antarctica.
There is also a saying that the five continents are the five Olympic rings, namely: Asia, Africa, Europe, America and Australia!
There are only four oceans, namely the Arctic Ocean, the Pacific Ocean, the Indian Ocean and the Atlantic Ocean.
The seven oceans mentioned in the "Saint Seiya" animation were the Arctic Ocean, the East Pacific, the West Pacific, the East Indian Ocean, the West Indian Ocean, the North Atlantic and the South Atlantic. To put it bluntly, it's still four oceans, there is no "eight oceans" as you call it.