Divergent plate boundaries primarily create mid-ocean ridges. At these boundaries, tectonic plates move apart from each other, allowing magma from the mantle to rise and create new oceanic crust. This process typically forms underwater mountain ranges known as mid-ocean ridges.
Trenches are associated with convergent plate boundaries, where one plate is pushed beneath another. Mountains can form at both convergent and transform boundaries but are not the primary landform associated with divergent boundaries.