In the article Ship Traffic Increases Dramatically, to Oceans' Detriment , there is a quote (emphasis mine) :
"I was surprised to see that in 20 years, the growth is almost fourfold, or almost four times larger," Tournadre said. "We are putting much more pressure on the ocean."
The speaker does not intend to use the phrase literally, but this makes me wonder if this is true. Does putting more and more ships on the ocean increase the pressure on the ocean bed? If it's true, it will imply that the pressure on a scuba diver (or any object under water) would increase because of the ship!
On the one hand, adding more weight on top of anything must increase the force it exerts on the ground, so the pressure must also increase. But on the other hand, since the ocean area is not strictly bounded, the ocean spreads out, so the pressure must decrease; hence the dilemma.
Though the effect may be negligibly small, I would still like to know if a ship can increase the ocean's pressure. If yes, by roughly how much?
This question explains the case for bounded fluids, it does not explain unbounded fluids like the ocean.