First of all, we should recognize that the idea of separate named oceans is simply something that we humans have made up. The oceans of the world are, of course, all connected to one another in one way or another. Because of that, we could actually say that there is only one ocean. When we decide to divide the global ocean up, we are doing so in a rather arbitrary way. Because this is so arbitrary, the number of named oceans in the world has changed recently even though the physical makeup of the world has not. There are now, in many people’s minds, five oceans rather than four.
The four oceans that are recognized by everyone are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean. In recent years, many people have come to accept the idea that there is a “Southern Ocean” that surrounds Antarctica. So, if you are supposed to name only four oceans, they are the Pacific, the Atlantic, the Indian and the Arctic, but many sources will also mention the Southern Ocean.