Final answer:
The buoyant force on you when you displace 350 N of water is also 350 N, according to Archimedes' principle.
Step-by-step explanation:
The buoyant force on you when you displace 350 N of water as you dive under is determined by Archimedes' principle, which states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid that the object displaces. In this case, since you displace 350 N of water, the buoyant force on you is also 350 N. This means the water is pushing up on you with a force of 350 N to support you in the water.