When Simon Holliday jumped into the water to swim from Hong Kong to Macau on 24 May 2014, he was feeling anything but ready. He certainly didn’t know this 5:30 am swim would break a world record; nor did he think it would attract an unlikely swarm of spectators.

About four hours into the 35km, 10:20:30 journey – part of the Clean Cross Swim to raise money for the Ocean Recovery Alliance’s anti-pollution initiative – open-water swimmer Holliday was approaching the mouth of the Pearl River Delta when his support paddler, Shu Pu, started yelling. There were endangered pink dolphins everywhere, as if they had signed up to join the race.

“I have been in Hong Kong, paddling around the islands for seven years, and have never encountered a pink dolphin on my own,” Pu said.

It wasn’t just one or two dolphins either – there were about 25 to 30 following the crew and diving on every side. “They stuck with us for more than an hour and came really close, probably 3m from me, jumping and crossing in front of my canoe,” Pu added. “We actually exchanged looks at one point, kind of acknowledging each other.”

The crew encountered another group of Chinese white dolphins – which are often called pink dolphins for their rosy hue – as Holliday closed in on Macau, as if they were rooting for him to cross the finish line. “I didn’t actually know they were there until the crew told me,” Holliday said. “And then I was thinking, well the sun is out, the dolphins are following along, and I might just finish this thing. It was a really great omen.”

Pink dolphin sightings these days are unusual enough to begin with – and it is unheard of to see so many in one place at the same time. According to the Hong Kong Dolphin Conservation Society, the number of pink dolphins in Hong Kong waters plummeted from 158 in 2003 to 61 in 2014 – a 40% decline. Other small populations of Chinese white dolphins – some with a slight pink tint, others appearing grey ­­– found near river mouths in Thailand, Vietnam and Malaysia, are also threatened.

Between the ongoing construction of the 50km Hong Kong-Zhuhai-Macau Bridge – which will be one of the longest bridges in the world upon completion at the end of 2016 – to the high-speed commercial ferries zipping back and forth to China every day, Hong Kong’s waters are teeming with physical threats and acoustic chaos. The latter is especially damaging because dolphins rely on sonar to navigate, communicate and find food. The government is also planning to build a third runway near the Hong Kong International Airport on Lantau Island, which is in a prime dolphin corridor. The project would involve 650 hectares of land reclamation, dramatically reducing the dolphins’ habitat and further restricting their movement.

“The situation has gotten a lot worse in the last decade. If development pressure keeps going at this rate, there is not much hope,” said Dr Samuel Hung, chairman of the Hong Kong Dolphin Conservation Society, an NGO dedicated to tracking dolphins and researching mortality causes.

But bridge and land development is only one issue. The animals also face serious threats from pollution, which leads to diseases and premature deaths of dolphin calves. Due to ineffective waste management, Hong Kong’s waters are highly contaminated with plastics, fertilizers and heavy metals, something the Clean Cross Swim is trying to raise awareness of.

There are also issues with unregulated tour operators. Many fishermen in the village of Tai O, near one of the dolphins’ corridors, operate small dolphin-spotting operations out of their tiny motorboats. Though some guides take the necessary precautions, many do not follow the Agriculture, Fisheries and Conservation Department’s voluntary code of conduct – which warns against approaching the dolphins at high speed, crowding around them, suddenly changing course or coming between a mother and her calf.

To try to remedy the situation, the WWF-Hong Kong introduced a four-month-long Dolphin Watching Interpreter Pilot Programme in July, where interpreters sporting “Dolphins, I care!” shirts accompany travellers on tours with four small Tai O-based motorboat operators to explain the dire state of affairs.

For travellers, the only eco-tourism operator dedicated to the pink dolphins is Hong Kong DolphinWatch. Founded by Bill Leverett, the company's mission is to raise awareness and funding for the blushing beauties.

“[Bill] looked at the best practices in eco-tourism – particularly whale and dolphin watching, around the world – and tried to implement the same standards here,” said company spokesperson Janet Walker. “He thought that if you put a monetary value on the dolphins then maybe people would think they’re worth saving.”

Today, the operation runs three half-day trips a week, departing from Tung Chung on the northern side of Lantau Island, with anywhere between 10 and 50 people aboard its 20m-long ship. The tour explores the dolphins’ favourite corridors, coming surprisingly close to the Hong Kong–Zhuhai–Macau Bridge where dozens of sledgehammer-like machines drive piles into the ocean floor.

The group trip has a 97% sighting rate, and the iconic dolphins delight travellers with their playful personalities and photogenic appearance. They typically surface in pods of two or three, sometimes for a split second, other times for a round of playful jumps, their bright cotton-candy hue a wonderful contrast to the deep green waters.

And not only is it a fun experience for travellers, but learning about the human encroachment that these dwindling dolphins are up against every day is one more step towards saving these beloved creatures.

You may not be able to swim alongside the pink dolphins quite like Simon Holliday did, but with continued efforts by activists to educate travellers and operators alike, the pink dolphins may very well be diving around Hong Kong waters for a little while longer.