I am working on a projekt and have stumbled upon a problem. Lets say you have a "cat" that is completly submerged in water and is swimming downwards.

You are given the buoyancy on the cat.

You are given the gravity on the cat.

You are given the volume of the cat, like for instance 35cm^3

You are given the weight of the cat, like for instance 80g=0.080kg

How can i calculate the minimum force the cat has to provide to swim downwards in constant speed?

Also if the cat has to reach a depth of 400cm, how i can calculate the force needed for that?