Highest altitude Mars landing

NASA's (USA) Mars Exploration Rover Opportunity landed successfully at Meridiani Planum on Mars on 25 January 2004 at an altitude of -1.38 km (-0.85 miles) relative to the MOLA Geoid. With the absence of any sea on Mars with which to establish 'sea level', the MOLA Geoid (Mars Orbiting Laser Altimeter) is essentially 'sea level' on Mars.