What is the name of the large crater that the Opportunity rover spent years exploring?

The large crater that Opportunity spent years exploring was Endeavour Crater.

Endeavour is an enormous impact crater roughly 22 kilometers (14 miles) across, far larger than the smaller craters Opportunity had visited earlier. Scientists selected it as a destination because orbital observations revealed exposed rocks along its rim that appeared to be much older than most previously examined by the rover.

Opportunity reached Endeavour’s western rim on August 9, 2011, after driving for nearly three years from its earlier exploration area. The rover investigated portions of the rim, including Cape York, Solander Point, Marathon Valley, and Bitterroot Valley. These locations contained geological evidence of ancient water activity, including clay minerals and sulfate-bearing rocks.

A common mix-up is Victoria Crater, which Opportunity explored before Endeavour and entered in 2007. Gale Crater was Curiosity’s landing site, while Jezero Crater became Perseverance’s destination. Opportunity continued working around Endeavour until communications ended during a planet-wide dust storm in 2018.