The river was also cold, causing his muscles to cramp when he hit the water.
The United States Geological Survey (USGS) showed the river’s temperature last week at about 22 to 23 degrees Celsius, much lower than what a Singaporean would be used to.
When asked if there were moments he felt like giving up during the gruelling swim, Dr Chua replied, chuckling: “Oh, 100 per cent.”
“In those moments, it was really about hanging on to those little nuggets of strength that kept me going no matter how tough it got,” he told CNA938.
However, the marathon swimmer said the uncertainty of success made the challenge all the more alluring.
“If there was a 100 per cent chance of completing the swim, then I probably wouldn’t have been so passionate about wanting to take on this challenge. It would have taken away a lot from the sacrifice and the hard work put into it,” he said.
“I think there’s a bit of joy, challenge and satisfaction in aiming to do something that might just be out of your grasp.”