Easter Island and surrounding islets, such as Motu Nui and Motu Iti, form the summit of a large volcanic mountain rising over from the sea bed. The mountain is part of the Salas y Gómez Ridge, a (mostly submarine) mountain range with dozens of seamounts, formed by the Easter hotspot. The range begins with Pukao and next Moai, two seamounts to the west of Easter Island, and extends east to the Nazca Ridge. The ridge was formed by the Nazca Plate moving over the Easter hotspot.