Sea-Floor Spreading is your answer.
New oceanic crust is created at the mid-oceanic ridges, a divergent plate boundary.
You would find a mid-ocean ridge at an oceanic-oceanic plate divergent boundary. This ridge is formed by the spreading apart of the two plates, allowing magma to rise and create new oceanic crust.
The Divergent Boundaries.
A real example of oceanic to oceanic divergent boundary is the Mid-Atlantic Ridge. This underwater mountain range runs along the floor of the Atlantic Ocean, where it separates the North American Plate from the Eurasian Plate to the east and the African Plate to the west. As the plates move apart, magma rises to the surface, creating new oceanic crust.
It forms a convergent boundary with the South American Plate, divergent.
The landforms that could develop at a continental and oceanic divergent plate boundary includes; Rifts and Volcanic Mountains.
Divergent plate boundary.
The mid-ocean ridge is a divergent plate boundary where tectonic plates are moving away from each other. As the plates separate, magma rises to the surface, creating new oceanic crust.
The East Pacific Rise is a divergent plate boundary where tectonic plates are moving apart. This boundary is associated with seafloor spreading and the creation of new oceanic crust.
The Mid-Atlantic Ridge is formed where the Eurasian Plate and the North American Plate are diverging, creating a boundary known as a divergent plate boundary. As the plates move apart, magma rises from the mantle to fill the gap, creating new oceanic crust.
The Mid-Atlantic Ocean is a divergent plate boundary, where tectonic plates are moving away from each other. This movement creates new oceanic crust as magma rises from the mantle and solidifies at the mid-ocean ridge.
The African Plate and Antarctic Plate are separated by a divergent plate boundary known as the Mid-Atlantic Ridge. Here, the plates are moving away from each other, leading to the formation of new oceanic crust.