They huddled in a remote corner and were swigging from bottles of alcohol that cost about $40 each.
Just as they were about to make merry, police officers swooped in and told them to stop drinking, and to dispose of their opened alcohol bottles.
Their party was over even before it began.
Wednesday was the first day that the Liquor Control (Supply and Consumption) Act took effect.
Under the new law, drinking in public is banned after 10.30pm and shops are also not allowed to sell takeaway alcohol.
Residents at Robertson Quay have long complained about clubbers who have been leaving plastic bags and empty bottles behind after drinking.
Cleaners from Veolia Environmental Services that The New Paper followed a month ago said they faced difficulties cleaning up after the revellers. When TNP went to Robertson Quay on Wednesday at 9.30pm, there were about three groups of revellers sitting behind the Grand Copthorne Waterfront Hotel.
The two bridges nearest Zouk, most commonly used by revellers as drinking venues, were empty at the time. But the real action started only at 10.30pm, when the drinking crowd behind the hotel grew sizably.
Some among the crowd, who turned out to be plainclothes policemen, stood up and started telling the rest that it was illegal to continue drinking alcohol to disperse the crowd.
These policemen went around telling anyone who was drinking alcohol to stop and made them throw their alcohol bottles into dustbins.
One drinker, who wanted to be known only as Mr Chua, said: "I thought as long as we didn't cause trouble, the authorities would leave us alone. Who knew they would stop everyone from drinking?"
By 11pm, police had cleared out the last of the drinkers.
No one was seen drinking by the time TNP left at about midnight.
TNP understands that cleaners in charge of the area reported collecting less rubbish on Wednesday.
Meanwhile in Geylang, which has been designated as a liquor control zone, things were slightly different.
There were just a sprinkling of men, mostly foreign workers, who were sitting around drinking cans of beer. Most were drinking alone.
MP for Marine Parade GRC Fatimah Lateef and about a dozen grassroots volunteers went around the area between Lorong 34 and 40 to hand out fliers educating residents about the restrictions. They were accompanied by two Community Policing Officers.
A construction worker, who wanted to be known only as Mr Wei, was drinking with some friends at a five-foot way at Geylang Lorong 36 when the group approached him at about 10pm.
"We had heard of the new regulations but we weren't sure when they started," the 45-year-old said in Mandarin. "Now we'll just drink in our dormitory."
'Light touch' in initial phase
The police will take a measured response in the initial period of new alcohol restrictions coming into effect.
For now, their roles will be more educational and advisory, as they try to get the message across to members of the public about the ban on drinking in public after 10.30pm.
Superintendent Koh Tee Meng, assistant director of operations management division, told reporters on Wednesday: "In this initial phase, police will take a light-touch approach and advise the public who are found drinking in public places during the restricted hours. So, it is more of an advisory and educational approach."
But those who repeatedly violate the regulations can expect to face the full brunt of the law, he added.
In Geylang, MP for Marine Parade GRC Fatimah Lateef addressed the concerns of shopkeepers worried about the law's impact on business.