The swimmer had plunged into the sea in the middle of a huge fog.
A senior Dubai police chief rescued a drowning man on Thursday morning.
Lieutenant-General Dhahi Khalfan Tamim, Dubai’s Deputy Chair of Police and Community Safety, said the swimmer plunged into the sea amid heavy fog that covered the train on Thursday morning.
After losing consciousness, he went missing and shouted for help, a police officer said on Twitter.
“We rescued him and took him to shore in our boat,” said a security official.
Lieutenant General Tamim warned residents to swim in the sea amidst foggy conditions.
Dubai and parts of the UAE saw dense fog in the morning twice straight. On Wednesday, a 26-car accident caused by fog left a woman injured.