The 40-metre high Rain Vortex, which is the world's tallest indoor waterfall, is seen from inside Jewel Changi Airport in Singapore, April 11, 2019. A sprawling retail complex with the world's tallest indoor waterfall is what Singapore hopes will bring more travellers and visitors to the airport to shop and dine. REUTERS/Feline Lim

The 40-metre high Rain Vortex, which is the world's tallest indoor waterfall, is seen from inside Jewel Changi Airport in Singapore, April 11, 2019. As global competition for travellers heats up in the aviation industry, Singapore's Changi Airport is set to open its S$1.7 billion ($1.3 billion) Jewel complex on April 17. REUTERS/Feline Lim

People sit in the Changi Lounge of Jewel Changi Airport in Singapore, April 11, 2019. Changi Airport, recently voted in a Skytrax survey as the world's best for the seventh year running, reported a record 65.6 million passenger movements in 2018. REUTERS/Feline Lim

The reflection of the roof of Jewel Changi Airport is reflected in a pond in Singapore, April 11, 2019. REUTERS/Feline Lim

A woman poses for a picture at the Canopy Park of Jewel Changi Airport in Singapore, April 11, 2019. REUTERS/Feline Lim

The 40-metre high Rain Vortex, which is the world's tallest indoor waterfall, is seen from inside Jewel Changi Airport in Singapore, April 11, 2019. REUTERS/Feline Lim