Tourists in vehicles stopped to snap photos and video of the big cat, noting that it seemed to be injured as it was walking slowly with a slight stumble and did not run away at the sight of humans.
However, after watching the footage, park officials concluded that the black panther was in good health.
They speculated that the creature may have been strolling along the road to benefit from the warm sunlight on the cold morning.
Only about 10 panthers and smaller leopards have been spotted in the area since trail cameras were installed in 2013, said park chief Mongkol Chaiphakdi.
Panthers and other leopards are shy and solitary creatures that do not normally attack humans, often running away when they see tourists, he added.
However, he cautioned that anyone who spots these big cats should not exit their vehicles.
“Avoid making loud noises and using flash photography. They normally run away on their own,” he added.
Kaeng Krachan is Thailand’s largest national park at 2,915 square kilometres and home to gaur (wild bulls), elephants, dusky leaf monkeys, gibbons, and hornbills. The park also hosts Thailand’s only population of ratchet-tailed treepie, a lowland-forest bird with a distinctive long, notched tail. It was enshrined as UNESCO World Heritage under the name of the Kaeng Krachan Forest Complex in 2021.