Which ocean is growing in size which is shrinking and why is it occurring?

The Atlantic Ocean is growing in size due to the process of seafloor spreading at the Mid-Atlantic Ridge, where tectonic plates are moving apart and new oceanic crust is being formed. In contrast, the Pacific Ocean is shrinking as it experiences subduction, where the Pacific Plate is being forced under surrounding plates, leading to the destruction of oceanic crust. This dynamic is part of the Earth's plate tectonics, driven by mantle convection and the movement of tectonic plates.