Cuc Phuong National Park seen from above. (Photo: Facebook of Cuc Phuong National Park)

Cuc Phuong spans 22,408 hectares and is a nature reserve and special forest belonging to Ninh Binh, Hoa Binh and Thanh Hoa provinces. (Photo:cucphuongtourism.com.vn)

Cuc Phuong, Vietnam's first national park, is one of the gems of forest ecology. (Photo: Facebook of Cuc Phuong National Park)

Road down to the Peripheral Conservation Area. (Photo: Facebook of Cuc Phuong National Park)

An autumn day in Cuc Phuong (Photo: Facebook of Cuc Phuong National Park)

Cuc Phuong stream (Photo: Facebook of Cuc Phuong National Park)

This place is particularly special because of the green vegetation that has been nurtured and developed over thousands of years. (Photo: Facebook of Cuc Phuong National Park)

It’s also home to hundreds of rare animals (Photo: Facebook of Cuc Phuong National Park)

A red-cheeked gibbon (Photo: Endangered Primate Rescue Center)

A loris receives periodic health check (Photo: Facebook of Cuc Phuong National Park)

The "butterfly season" and “firefly season” in Cuc Phuong takes place every year, from mid-April to June. (Photo: Facebook of Cuc Phuong National Park)

Cuc Phuong is one of few places in Vietnam to witness the large gathering of over 400 species of butterflies. (Photo: Facebook of Cuc Phuong National Park)

The light from fireflies creates an enchanting space. (Photo: Vnexpress)