People walk on a road in the forest of Singapore's Central Catchment Nature Reserve on April 21, 2021. (Photo: Xinhua)

The morning sun rises from the forest in Singapore's Central Catchment Nature Reserve on April 21, 2021. (Photo: Xinhua)

Workers ride on a boat in Singapore's Central Catchment Nature Reserve on April 21, 2021. (Photo: Xinhua)

The morning sun rises from the forest in Singapore's Central Catchment Nature Reserve on April 21, 2021. (Photo: Xinhua)