The aging rover beamed new images to Earth on Wednesday, confirming it reached the hill informally called Cape Tribulation.
Opportunity landed on Mars more than a decade ago and has recently suffered bouts of amnesia stemming from an issue with its flash memory.
The six-wheel rover has been able to drive despite the occasional memory lapse.
Opportunity will spend several days at the summit snapping pictures that engineers will stitch into a colour panorama.
Project manager John Callas says the rover will try to find interesting rocks to study. If there are none to be found, it will keep driving.
Opportunity rover takes in view from top of Martian hill
These images sent by NASA's Opportunity rover on Wednesday, Jan. 7, 2015 shows a view from atop a Martian hill.
Opportunity will spend several days at the summit making pictures that engineers will stitch into a color panorama. (AP Photo/NASA)