CHONGQING, July 16 (Xinhua) -- Hit by a recent scorching heatwave, southwest China's Chongqing Municipality has seen temperatures soar to as high as 40 degrees Celsius. Yet amid this sweltering heat, visitors can still find a cool tropical rainforest right in the heart of the city.

At a shopping mall in Chongqing called The Ring, a lush indoor rainforest featuring towering tropical plants, cascading waterfalls and meandering streams has emerged as a popular summer getaway. While the city endures sweltering outdoor heat, the temperature inside this indoor oasis remains at around 21 degrees Celsius, providing visitors with a refreshing escape from the very high temperatures outside.

Xiao Shan, a tourist from Beijing, was captivated by the cool, futuristic ambiance of the space. "The afternoon heat makes outdoor activities nearly impossible, but here it feels like stepping into the world of Avatar, which is cool, surreal and perfect for family outings with children," she said.

Chongqing has long been dubbed one of the country's "furnace cities" due to its notoriously hot and humid summers. Nestled on the eastern rim of the Sichuan Basin and encircled by mountains, the city frequently endures extremely high temperatures in summer. In 2025, some districts recorded temperatures surpassing 43 degrees Celsius.

To help residents beat the heat, the city has rolled out a variety of creative cooling initiatives that integrate nature, technology and public services.

This summer, the shopping mall has enhanced its tropical rainforest experience by introducing more exotic plants, misting systems and atmospheric lighting. The interplay of verdant foliage, fine mist and light produces a striking effect, enveloping visitors in a cool and immersive jungle-like environment.

But Chongqing's way of coping with high temperatures goes far beyond creating indoor cool spaces. In the Chongqing Jiangbeizui Central Business District, the exterior walls of office buildings are almost devoid of traditional outdoor air-conditioning units, and yet they remain cool indoors. The secret behind this is a river-water source cooling system that uses the Jialing River as a natural cold source.

The system leverages the temperature differential between the river water and its ambient surroundings. Using heat pump technology, it channels the heat generated by buildings during summer into the river, where it is dissipated by the cooler water flow. By reducing reliance on conventional outdoor air-conditioning units, the system not only improves building aesthetics and lowers noise levels, but also minimizes heat emissions.

"Compared with conventional central air-conditioning systems, this cooling system can reduce energy consumption by approximately 30 percent, while also helping to mitigate the urban heat island effect," said Tang Shijie, an engineer at Chongqing Jiangshuiyuan heat pump energy saving technology Co., Ltd.

Beyond technological cooling solutions, Chongqing has been steadily improving its public cooling services. This summer, 158 rail transit stations across the city have opened free cooling zones, offering passengers rest areas, drinking water, heatstroke prevention medicines and mosquito repellent supplies.

These cooling zones are mainly located near residential communities, schools, hospitals and commercial districts, making them easily accessible to the elderly, students and outdoor workers. Meanwhile, the designated areas have been carefully planned to avoid impeding normal passenger flow, providing citizens with temporary shelters from the sweltering heat without impacting those on the move.

Another distinctive cooling method in Chongqing lies underground, hidden within the city's mountainous terrain. Since the 1930s, Chongqing has built a large number of air-raid shelters in its hillsides. Protected by the surrounding rock formations, these underground spaces remain cool in summer and warm in winter. Even on the hottest days, the temperature inside the tunnels stays at around 18 degrees Celsius.

Since 2002, many disused air-raid shelters have been converted into free public cooling centers. Over the past two decades, these shelters have hosted more than 26 million visits.

Today, these underground spaces have taken on new life. Some have been transformed into museums, restaurants, bookshops and performance venues. The "Underground City Old Teahouse" in Liangjiang New Area, covering an area of 4,500 square meters and capable of accommodating over 200 tables, exemplifies Chongqing's innovative use of its underground spaces.

From indoor rainforests and river source cooling systems to rail transit cooling zones and air-raid shelters, Chongqing is exploring diverse approaches to turn the challenge of high temperatures into opportunities in its pursuit of urban innovation.