The Lost City of Faar (Pendragon Series #2)

In the second installment of this adventure series, Bobby Pendragon and his Uncle Press--a Traveler--are on the water world of Cloral. Something has happened to the underwater farmland and the crops are poisoned. The only hope is for Bobby to locate the legendary lost city of Faar, which may hold the key to Cloral's survival.
CLORAL
The second installment in an epic series of adventures Fourteen-year-old Bobby Pendragon is not like other boys his age. His uncle Press is a Traveler, and, as Bobby has learned, that means Uncle Press is responsible, through his journeys, for solving interdimensional conflict wherever he encounters it. His mission is nothing less than to save the universe from ultimate evil. And he's taking Bobby along for the ride.
Fresh from his first adventure on Denduron, Bobby finds himself in the territory of Cloral, a vast world that is entirely covered by water. Cloral is nearing a disaster of huge proportions. Reading the journals Bobby sends home, his friends learn that the desperate citizens of the endangered floating cities are on the brink of war. Can Bobby -- suburban basketball star and all-around nice guy -- help rid the area of marauders, and locate the legendary lost land of Faar, which may hold the key to Cloral's survival?