Time for water levels to equalize Suppose that someone dumps some quantity of water into the ocean somewhere. Also, assume that no other water level changes are occurring. How long does it take for the change in water level to "propagate" to the other side of the world?
 A: "An amount of time"
It completely depends how much water is dumped "dumped" into the ocean.
Other than that, we'd need to know how large the "connection" is between the two bodies of water. Eg water flowing into/out of the Mediterranean from/to the Atlantic has to travel through a fairly narrow passage. Between the Pacific and Indian oceans, however, the "gap" is huge.
Your question has far too many assumptions and not enough detail to even be able to approximate it, and any answer would only ever be an approximation without significant amounts of detail.
A: We can approximate this by assuming that information is passed only at the speed of sound in the medium and ignore all other affects (shape of the sea floor, depths, tides, weather, marine life, etc).
In this, case the speed of sound in water is about 1.5 km/s. For the Atlantic ocean, the distance from New York to England is about 2800 km, so it would take about 1900 seconds (30 minutes). For the Pacific ocean, it's about 8200 km from Japan to San Francisco; that journey would propagate in about 5500 seconds (90 minutes).
