From quiet beaches in Bali to empty rooms in Hanoi's hotels, pangs from China's economic malaise and weakening yuan are being felt across Southeast Asia's vacation belt.

A boom in Chinese outbound travel in recent years that stoked tourism across Southeast Asia is now in reverse gear. The abrupt decline of Chinese travelers is becoming a painful lesson for nations such as Thailand and Indonesia that had become overly dependent on Asia's top economy.

"The slump in Chinese arrivals and tourism spending is being felt throughout the region," said Kampon Adireksombat, Bangkok-based head of economic and financial market research at Siam Commercial Bank Pcl. "There's always a concentration risk when relying on one market, and many countries may not be able to find a replacement for growth fast enough."