Before I watched the following video it brought back a memory of mine. When we went on our first cruise we had to fly to Puerto Rico over the Atlantic Ocean.
As we flew at 30,000+ feet I stared out the cabin window for at least an hour trying to catch a glimpse of something below.
At some 6 miles above the Earth one can see 100's of square miles of surface below. One would think I'd have spotted at least one vessel. Perhaps a small plot of land. SOMETHING? ANYTHING? NADA!
My perception of just how huge and remote this Earth can be changed that morning. My imagination wandered into thoughts of the near impossibility for rescue in this remote area if one were to be run into trouble even if the plane were to survive the impact. This wasn't fear, but more like 'wow we sure are in the middle of nowhere'. Throughout my life there's been a tree, a street or building. There's no way one could orient themselves when there's nothing to orient to. There's something new and weird about being humbled by the sheer vastness of it all.
I did this same kind of observation aboard the ship some 11 decks above sea level. Except for occasionally spotting a passing ship I saw nothing. For me personally when it comes to the size of the sea I have a much greater appreciation of it then I did before that trip.
I was left with an sensation of how small we are in all of this vastness of this the Earth we call home. It also showed me how dependant we all are on familiar surroundings. So as you can see this wasn't just some trip, but also an opportunity to reflect, absorb and add to my experience in this life and the weirdness that ensues when we're removed from our everyday environment.
So when it comes to the question how big is the ocean, these thoughts best describe my personal sense of it.
Video Courtesy "TED Ed"