The River Indus is a major river in Asia. It mainly flows through Pakistan but also has courses through western Tibet and Northern India.
For this cache, you don't need to buy an air ticket. Indeed, you need a train ticket to Sheung Shui. River Indus in Hong Kong also known as Ng Tung River (梧桐河) is a river in the northeast New Territories. Tributaries of the river include Tan Shan River and Kwan Tei River. It collects other major rivers like Shek Sheung River and Sheung Yue River in Sheung Shui, and finally empties into Sham Chun River (Shenzhen River).
The cache is loacted at the "guessed" middle of River Indus. If you visit the cache on the 1st or 15th of every lunar month (初一十五), you may see people doing their regular 'money making' business - Free Captive Animals (放生) at the river bank near Lung Sum Avenue (龍琛路). Actually, they are reselling human feeding Snakehead (生魚) and Chinese Bullfrog (田雞). What they are doing is not set them free but killing them and all the indigenous creatures in the river.