KAGOSHIMA — Since Yaku Island was placed on the World Heritage list 16 years ago, tourism has been booming.

Some 390,000 tourists flocked to the 500-sq.-km island south of Kagoshima Prefecture in fiscal 2008, up from an estimated 210,000 back in 1993.

More than 100,000 mountain climbers were among the tide last year, sparking a sewage-disposal problem.