MMEA Region Four Commander ACP Mohamad Madun said the trio (centre) were brought in during an "Ops Paradise" prompted by a tip-off.
"The boat with the three on board were stopped off the waters of Mas-Mas, Tanjong Kiraz and Kalumpang.
"All of them failed to flee and further inspection showed that all three men were not carrying any documents," he said via a statement posted on Facebook.
According to him, a toy gun and two face masks were among items confiscated, as well as a speedboat and one boat engine.
He said also confiscated were a gas tank, two handphones, two torchlights and a plank. He said police believe they can facilitate investigations on nine robbery cases and engine theft in the district.