Question

What is the force that opposes the movement of an object through water??

Answer 1

In air, you'd call it air resistance, pilots call it drag.  In water, some call it
water resistance, or just plain drag. 

Whatever it's called, it's the friction between the object and the fluid, plus
the force needed to push the fluid out of the way to let the object get through.

Answer 2

Drag is the force that opposes the motion of a body through fluids including water