With the number of these unique mammals plummeting due to development, land reclamation and pollution, now is the time to see them before it’s too late.

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.

Read the full story on BBC Travel.