The simple but unsatisfying answer is “the terminal velocity of that object in water”.
Terminal velocity in air is not a universal constant. Humans terminal velocity is something like 150 mph if they’re in the skydiving flat pose and up to about double that in the “pencil” pose. Feathers are more like 2 mph. The SR-71 in an unpowered dive probably very near the speed of sound.
Terminal velocity for all those objects in water would be probably an order of magnitude smaller, but still unequal to each other.
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