Excluding inclement weather periods, completing one round-trip patrol takes over three hours. Between winter and spring, the river is biting cold, but Zhao steps right in every day, saying, "It's fine once you get used to it".

Although there are no developed roads in the protected area, it still does not stop people from sneaking in. "A momentary lapse can allow people to slip in unnoticed," he adds.

The checkpoint is near Chongqing and during summer, many people arrive to escape the heat. There is an iron gate that cannot fully block the riverbanks. During the non-flood season, it is possible to walk along the shallow riverbeds deep into the core protected area.

The couple can't relax for a moment from dawn until midnight. There are some people who, when told this is a core protection area and entry is prohibited, will leave, but some who don't respect the rules. The ecosystem is frail here and is home to many endangered species. They must report any trespassing to the management station and forcibly escort those people out.

Some people also enter through mountain trails for fishing or hiking. This is why patrols cannot be interrupted for even a moment. Along the way, if they find such individuals, they must persuade them to turn back. This is not only to protect the plant and animal habitat but also to ensure the visitors' safety.