Upwelling

Real World Example

Imagine you're at a crowded concert, and you drop your phone on the ground. Just like how you have to work your way through the crowd to retrieve it, cold water from the deep ocean has to push through layers of warmer water to reach the surface. In both cases, whether it's you retrieving your phone or cold water rising, there's an upward movement against resistance, where something from below moves upwards to the top.