The magnitude of the buoyant force is equal to the weight of the fluid displaced.
The direction is always vertical, and depends upon the density of the object.
  1. density: density = mass(kg)/volume(m3)
  2. specific gravity: ratio of an object's weight and the weight of the same volume of water

What is the mass, volume, and density of the human body?

What is the specific gravity of bone, muscle, and fat?
 

 

The buoyant force acts through the center of volume;

This force may not be especially important for some to consider, but it is for others...

Also, keep in mind that buoyant forces exist on land, with much smaller magnitudes.

With this in mind, how might you manipulate the center of weight to float more easily?

What are other tactics one might employ to float or sink?