Singapore adventurer Khoo Swee Chiow in the tank
Singapore adventurer Khoo Swee Chiow begins his bid for the Guinness World Record's longest scuba dive on Friday.
The current record of 212 hours 30 minutes was set in 1986.
Khoo literally went underwater at 3.34pm in a special mineral water tank at Tampines Central.
He hopes to emerge nine days later - past 12.04pm on Christmas Day - to set a new world record.
Until then, he will not be allowed to surface - though he can take a five minute break every continuous 60 minutes.
Khoo is expected to face several challenges like dehydration, nausea and vertigo, and divers from Fisherman Scuba and Singapore Civil Defence Force paramedics are standing by, just in case.
But one greatest challenge the seasoned adventurer himself acknowledged is beating 212 hours and 30 minutes of utter boredom