The To Sua ocean trench of the Pacific plate in Samoa

Oceanic-Oceanic Crust Collision

Another type of convergent boundary occurs when an oceanic plate collides with another oceanic plate. The more dense plate, like always, subducts under the less dense plate, creating a subduction zone called a trench, thus being responsible for ocean trenches and island chains:

The Japanese Islands of the Eurasian Plate

Convergent Boundaries: