A piece of wood would appear lighter in water but that is because the buoyancy force counteracts the weight.

This difference in pressure causes the upward buoyancy forces.

The buoyancy force exerted on a body can now be calculated easily, since the internal pressure of the fluid is known.

The magnitude of buoyancy force may be appreciated a bit more from the following argument.

We can also safely assume buoyancy forces are negligible for these objects.

The primary buoyancy force is provided by air pressure acting on the underside of the deck.

The result is either a positive or negative buoyancy force.

Objects in water feel the upward buoyancy force from the water.

You feel an upward buoyancy force from the air, as does a helium balloon.

This makes less of the object be in the water, so that upward buoyancy force is smaller.