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I think you are incorrect. If you build a 230-m tall pipe and fill it up with water, the water at the ground-level end of the pipe will be at the exact same pressure as the water 230 m deep in the ocean. Hydrostatic pressure only depends on the depth, not the container shape.

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Uh no?

The water at the ground level on the ocean will have the same pressure as the water at ground level in the pipe. The water at 230m down in the pipe will be the same as the water 230m down in the ocean.

Even if the pipe is capped on both ends.

a pipe 230m tall with the bottom at ground level would experience the same hydrostatic pressure as water 230m under the ocean. the pressure comes from the weight of water above it, not distance from sea level. this is literally how water towers work.

That is literally what I said, yes.

The post I replied to said the opposite - that the pressure at the surface of the ocean would be the same as the pressure at the end of a pipe going under water, if there was a pipe.

Which clearly isn’t true or we’d have a trivial perpetual motion machine.

Edit: it looks like they changed their post?

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