On May 31, Thailand's much revered King Bhumibol Adulyadej was admitted to a Bangkok hospital after returning from his seaside palace at Hua Hin just three weeks before. He was accompanied by his ailing wife, Queen Sirikit, who suffered a stroke in 2012. Their latest hospitalization is sparking speculation about the looming end of the Bhumibol era.

On the throne since 1946, Bhumibol is the world's longest-reigning monarch. But his deteriorating health has caused anxiety among Thais about what will come next. This nervousness is partly due to the generally uncertain political environment now that the nation is once again in the custody of a self-appointed military government. But it is also the result of Bhumibol's reign having been perhaps too successful: Can his successor match up?

Revered by the military, bureaucrats, big business and mainstream society alike, the king is extolled in schools and the media as both a demigod and a monarch. Photos released by the palace show him traveling through remote regions with maps and cameras in hand, a trickle of sweat on his brow.