The deeper you dive into the ocean and the higher the altitude you gain when climbing a mountain result in what?

A change in pressure

Explanation:

This is because, the deeper you dive, the height of water above you creates a pressure on you. So, as the depth increases, the height of water increases, thus its weight on you, thus its pressure on you also.

Also, as you gain altitude as you climb a mountain, the height of air above you decreases. This thereby decreases the weight of air above you thus, decreasing the pressure of air on you.

So, in both cases, there is a change in pressure as height or depth changes. An increase in height results in decreased pressure and an increases in depth results in increased pressure.