What is meant by suggesting that earth’s oceans are connected?

I am unsure of how to answer this completely, but I will give it my best.

It could be meant that there is no physical boundary holding them apart and that the world's oceans simply flow into each other rather than being separated. Such as the pacific and Atlantic. They are not held apart, they flow around countries and flow into each other at a certain point.

Answerstratovolcanoes///near or in the ring of fire;