WHERE RUNS THE RIVER

GLINDING UNDER

BANGKOK’S RAMA VII BRIDGE gives me a huge thrill. I’m giddy, elated. Which seems to surprise Noom, my guide aboard the Manohra Dream: we’ve seen a number of more impressive bridges since the boat pushed off from its jetty an hour ago. Compared to the Taksin Bridge downriver near where I live, or the elegant, gilt-cabled span of the Rama VIII, the Rama VII is an ugly duckling—concrete, low hanging, utterly utilitarian. Hardly worthy, I suspect Noom thinks, of Thailand’s mighty River of Kings, the Chao Phraya.

But it’s not the bridge that has me excited. Rather, it’s the otherwise invisible transition it marks: the end of Bangkok and the beginning of Nonthaburi Province. Sixty kilometers upriver from Bang Pu, where the Chao Phraya empties into the Gulf of Thailand amid fleets of fishing vessels and flocks of seagulls, I am finally embarking on a quest that’s been months in the making—to travel to the river’s headwaters, then follow its course all the way back to the sea. Though I’ve lived along the banks of the Chao Phraya for six years now, like most residents in the capital, I’m really only familiar with the busy, canal-edged stretch that passes though Bangkok. My mission now is to explore its entire nation-defining length.

in the central Thai province of Nakhon Sawan, where several tributaries stream down from the kingdom’s northern hills. The biggest, the Ping and Nan, flow from Chiang Mai and the mountains bordering Laos, respectively, meeting at an area called Pak Nam Pho to form a river that, while neither particularly long (less than 400 kilometers) nor particularly deep, is the lifeblood of Thai civilization. All current and former Thai capitals are situated along, or linked to, the Chao Phraya, which nurtures much of the country’s agriculture and over half the entire