In what the National Parks Board (NParks) has called "a rare occurrence", several visitors to Sungei Buloh Wetland Reserve came across a saltwater crocodile lying across the main footpath.
On Nov 20, a teacher and a small group of seven-year-old schoolchildren from the United World College of South East Asia (UWCSEA) encountered the crocodile while on a field trip.
It entered the water after the teacher and another visitor approached it tentatively.
The group returned to the reserve's entrance immediately after that.
The saltwater crocodile, notorious for attacks on people in parts of Australia and East Malaysia, is the world's largest living reptile and one of the most vicious predators known to man. It had been common here 40 years ago before being hunted close to extinction.
The crocodile had been about 20m ahead of the schoolchildren, who were asked to stop and wait quietly, said a UWCSEA spokesman.
"No one was alarmed or worried," she added.
Photographer Richard Seah, 58, the other visitor, estimated that the crocodile, which stretched across the entire width of the path, was 3m long.
"It was pretty still, so I wasn't afraid. But thinking back, if it decided to attack me I probably could not have outrun it," said the regular visitor to the reserve.
Up to 10 saltwater crocodiles are estimated to live in Singapore waters around the north-western coastline, up from two in 2008.
There have been regular sightings in recent years in Sungei Buloh and around Kranji Reservoir.
Experts say some may have been forced out of Johor waters by development there, and that their presence here is a sign that protected habitats such as Sungei Buloh are flourishing.
NParks director for conservation Wong Tuan Wah said that the crocodiles in Sungei Buloh are usually found in the water or at mudflats away from visitor routes.
Visitors should heed the warning signs in the reserve, he said, sticking to paths and staying calm and backing away slowly if they encounter a crocodile.
He added that NParks will be monitoring the situation to ensure public safety. More than 100,000 people visit Sungei Buloh each year, including many school groups.
Dr Benoit Goossens, a wildlife conservationist who studies saltwater crocodiles at the Danau Girang Field Centre in Sabah, Malaysia, reiterated experts' views that there is "realistically very little" danger to the public as long as people heed safety notices and behave responsibly.
Reptile expert and National Geographic Channel host Brady Barr especially cautioned people against feeding them.
"The real danger starts when crocodiles start associating people with food," he said. He too stressed that there was no need to panic as the risk was "very minimal".
But he called for the authorities here to study and track the local crocodile population so they can monitor them better.
"That way you know what you're dealing with," Dr Barr told The Straits Times.