Here's why:

* Convergent boundaries are where two tectonic plates collide.

* When an oceanic plate collides with a continental plate (oceanic-continental convergence), the denser oceanic plate is subducted (forced) beneath the continental plate.

* As the oceanic plate descends into the mantle, it melts due to the intense heat and pressure. This molten rock can rise to the surface, creating volcanoes and forming new land.

* When two oceanic plates collide (oceanic-oceanic convergence), the older, denser plate will subduct beneath the younger, less dense plate. This process also leads to volcanic activity and the formation of island arcs.

In essence, the process of subduction at convergent boundaries destroys the oceanic crust by melting it and recycling it back into the mantle.