What are the huge underwater mountain ranges that present in every ocean?

The underwater mountain ranges present in every ocean are called mid-ocean ridges. These are massive mountain chains that run along the boundary between two tectonic plates and mark the sites of seafloor spreading. The mid-ocean ridges are characterized by volcanic activity and hydrothermal vent systems that support diverse ecosystems. They play a crucial role in the cycling of nutrients and heat within the Earth's oceans and contribute to the planet's overall geological and biological processes.