Another way to observe the buoyancy of water
Push a large cork to the bottom of a pail of water. Notice the quantity of force you have to apply to hold the cork at the bottom. Repeat the experiment using a fairly large empty bottle stopped with a cork. Is there any dissimilarity in the force needed?
Blow up a toy balloon and push it to the bottom of the pail. How does the force to hold it down compare with the force needed for the cork and bottle?