Hangzhou Day Trip: Great Heat Is Here, Yet This Place Stays a Constant 18°C – Cool Off This Summer!

“In summer’s heat, you forget the scorching sun; a winter visit feels like spring. Though the source is one stream, its crystal clarity belongs only to Chuiyun.” This describes an underground karst river in Tonglu, Zhejiang — the Chuiyun Tongtian River.

With the arrival of Great Heat (the peak of summer), finding a place that’s beautiful, fun, and refreshing enough for a day trip has led me to Tonglu, near Hangzhou — a new favorite.

I rounded up a few friends and we set off by car. The drive from Hangzhou to the scenic area took about two hours, an easy journey.

Nestled in lush green mountains and clear waters, there’s always something to explore.

Thanks to crustal movements and volcanic eruptions hundreds of millions of years ago, a classic karst landscape took shape here, full of bizarre shapes and colors — like scenes straight out of 'The Lost Tomb' by Nanpai Sanshu. This is the Chuiyun Tongtian River, hailed as the number one underground river.

We boarded a wooden boat and drifted across the emerald-green lake. Black swans swam leisurely beside us, splashing and playing.

The moment we entered the cave opening, a wave of chill greeted us. The temperature here stays a constant 18°C all year round, and the water is crystal clear. The scorching heat of summer vanished in an instant.

Inside, the karst formations are well-developed, with abundant underground springs, sweet and pure water, and fresh air. Water gurgles year-round along the winding, deep-set channel, forming pools, lakes, and even rapids and cascades — an ever-changing scenery that’s hard to leave.

Due to recent heavy rains, the underground river’s water level was high. Many stalactites hung so low we could almost touch them — we had to duck to pass, or risk bumping our heads.

All the stalactites here are alive, so water still drips from some. It’s said they only grow about 1 cm every 100 years. Our guide, a seasoned staff member, gave detailed explanations and set a perfect pace.

Close up, the stalactites truly resemble all sorts of shapes — sharks, penguins, jellyfish, mushrooms, a Buddha’s hand — incredibly lifelike.

The river follows a one-way route. Visitors disembark at the end and don’t come back, but the boats return to the starting point. The whole waterway is a winding, secluded path that varies in width — at its narrowest, only a single boat can squeeze through. It’s perfect for those with a sense of adventure.

The lighting inside the cave is excellently done, reportedly the result of several renovations.

In the middle section, there’s a spot called 'Cave Heaven Buddhist Kingdom' where you can disembark — the only stop on the boat tour. It features three natural wonders known as the 'Three Wonders of Chuiyun,' the biggest highlights of the underground river.

The first wonder is the 'China Map' — layered formations that resemble terraced fields, a type of karst feature formed by calcium carbonate deposits washed down from above.

The second is the 'Guanyin Stone Statue,' located inside a yurt-shaped hollow carved by sheet-like water flows. The third is a 'Natural Stone Dragon,' where you can clearly make out the dragon’s head, body, and tail.

Visitors can walk through stone pillars into a relatively open area, and then the boatman will be waiting for you at the dock there to reboard.

Back on the boat, we encountered the river’s most spectacular stalactite — soaring straight upward as if reaching for the sky.

We also passed through a colorful jellyfish zone and a realistic, animated shark area.

The final highlight came near the end: a colorful light tunnel that felt like a time-space portal, which took the boat straight to a large disembarkation area, wrapping up our underground river journey.

The whole experience was fantastic! Most importantly, it was wonderfully cool inside. Leaving this cozy, magical natural air-conditioner was genuinely hard. The moment we were back on the surface, the 35°C heat hit us, and my glasses and camera instantly fogged up. That was the biggest temperature shock I’ve ever experienced on a summer trip.

At the end of the river, there’s a forested area of nearly 30 square kilometers. Looking into the distance, you can see a silvery necklace suspended in the sky — that’s the heart-pounding 'Lingyun Glass Bridge.'

Getting from the underground river to the Lingyun Bridge requires climbing a long flight of stairs — save your energy! Once you see daylight, you’ll spot the 'Angel Corridor,' a white arch covered in flowers. Walk through it and you’ll reach the classic photo spot: the 'Angel Wings.'

Behind the Angel Wings are transparent glass and lush green woodlands. From afar, it looks like a fairy spreading her wings and flying through the mountains. So dress a bit ethereal for photos — you’ll look even better on camera!

After a few more photo spots, we reached the thrilling glass walkway: the Lingyun Glass Bridge.

This Lingyun Glass Bridge stretches over 300 meters, suspended by cables above a chasm hundreds of meters deep. The moment you step on it, you’re bound to scream! ‼️

After putting on shoe covers, I inched forward. I found that after a few steps, the bridge would wobble — that feeling of uncertainty high above really is frightening.

That first step felt a bit disorienting. My tip: keep your eyes forward, don’t look down — it helps a lot.

If you’re not great at psyching yourself up, you might chicken out. A little bolder, and you’ll manage a few steps. But if you have a serious fear of heights, just skip it.

The glass here is incredibly transparent — everyone wears shoe covers to protect it, so it stays pristine. Through the thin pane, you can see the world below all the way down to the foot of the mountain 🌅 a dizzying drop.

From a distance, this silver-gray glass suspension bridge looks light and crystal clear, especially vivid under the sun. We flew a drone to capture it from another angle.

Walking alone across it, looking far into the endless green, it felt as if the whole sky and land were mine. Feeling braver, I hummed a tune and even jogged along the walkway, racing through the jungle canopy — it was incredibly liberating and therapeutic.

Getting off the bridge, we headed straight for the super fun 'Lingkong Drift' (Aerial Water Ride).

Playing in the water is the ultimate summer joy. The Lingkong Drift is also made of transparent glass, looking as though it’s suspended in midair. Two per boat, we donned raincoats and pants, hopped into a rubber raft, and slid down the glass chute.

Perhaps to prevent dangerous speeds, they don’t put much water in now, so we often got stuck midway. Thankfully, friends coming behind bumped into us, and away we flew!

In the scorching summer, splashing around like this is pure bliss.

If you love water activities, besides Chuiyun Tongtian River, there’s another spot nearby called 'Langshi Jintan' (Golden Beach) that’s also great for water fun.

Bamboo rafting, outdoor team-building, starry camping, rustic barbecues, and even farm-style clay stoves. If you’re lucky, you might catch a dragon boat race here!

Now that the Great Heat is upon us, if you’re in the south and seeking a cool escape, you can’t miss Chuiyun Tongtian River — a place to see, play, and photograph.

So, do you think this scenic spot is right for a summer trip? If you had the chance, would you come experience Chuiyun Tongtian River? Share your thoughts in the comments!

Ziman: Global travel writer and certified content creator across multiple platforms, having traveled to 7 continents, 70 countries, and both the South and North Poles.

Published travelogues include 'Clear Walks Under the Sun,' 'Encountering Artistic Vibes on the Road,' and more.