Does the water in a bath or sink go a different way down the drain depending on which hemispere you are in?
Yes the water will drain in different directions depending on which hemisphere you’re in. Usually this question is asked about toilet flushing, but I guess it’s still fun to answer even though you’re more interested in baths and sinks draining.
Water will drain in different directions depending on the hemisphere due to the Coriolis force, which is the force generated by the spinning of the Earth. To be specific, water will drain in a counter-clockwise direction in the northern hemisphere and a clockwise direction in the southern hemisphere.
As the Earth spins things are influenced, put a ball on a merry-go-round in a park and spin it as fast as you can and the ball will fall off. The spin creates an outward force, we don’t fly off the Earth due to the Earth’s gravity, but things are still affected by this force.
You can notice the Coriolis force in hurricanes, watch the weather in your hemisphere and then watch it in the other hemisphere and you’ll notice the Coriolis force hard at work making sure storms are spinning in the proper direction.
This site has some more information that may interest you.