Sergeant Hizar Zahir regularly has to be crane-lifted onto an oil rig in a metal basket or climb onto a moving ship on a rope ladder.
Being an immigration checkpoints officer is hardly the desk-bound job many people imagine it to be - though perks include getting to see the odd dolphin frolicking in the ocean.
The Straits Times went behind the scenes with Sgt Hizar and four of his colleagues to see how they can "pre-clear" more than 1,000 foreign passengers on a cruise in around 90 minutes - all without compromising security.
On the day in question, they were due to board the 270m-long Superstar Virgo to pre-clear passengers' passports as it entered Singapore's waters.
This form of immigration clearance is unique to the cruise industry and is the reason why a cruise terminal can handle more than a thousand passengers every hour.
Sgt Hizar and four colleagues boarded a launch from their Brani Terminal base, each carrying a transparent backpack filled with the tools of their trade: a collection of passport stamps, inkpads, stationery and record sheets.
The waterproof backpack is see-through for a reason - to help prevent officers accepting bribes to wave people through. "It'll be very obvious if you bring a carton of cigarettes or a wad of cash back to shore," said Sgt Hizar.
The officers board the ship on a rope ladder as it slows down to enter Singapore. They take over a meeting room and spend an hour and a half stamping 1,000 passports from 19 countries.
It takes an experienced officer just 18 seconds to check a passenger's particulars against his visa and verify that the documents are authentic and valid, before stamping the passport and picking up the next one.
However this is just one of three kinds of checks a traveller faces before he is cleared to enter Singapore. After the pre-clearance, the stamped passport is checked electronically at the cruise terminal as the passenger is greeted face-to-face by an immigration officer. If there are any irregularities, the stamp is voided.
After the pre-clearance, cruise employees divide the stamped passports by nationality and into alphabetical order for collection, all while their owners lounge in their rooms or on the sundeck as the ship pulls into HarbourFront.
The "clearance-on-board" method is possible because cruises can provide their schedule a year in advance, said an Immigration and Checkpoints Authority (ICA) spokesman.
For now it is only used for the Superstar Virgo, which visits Singapore thrice a week, but it is likely to be expanded to other cruise liners - some of which can carry more than 5,000 passengers.
The ICA also plans to equip officers with a portable system that can perform the electronic verification of passports on board the ship, further reducing waiting times on land.
By 1.30pm, Sgt Hizar and his teammates are disembarking. A typical eight-hour shift sees a clearance officer board between 10 and 15 vessels, ranging from bulk carriers and tankers to tugboats and yachts, to conduct immigration clearance. Sgt Hizar says some days are particularly challenging, such as when he and his colleagues have to board a ship during bad weather or using "less ideal gangways and ladders". However he enjoys his job because of the variety of vessels he gets to board.
Although a cruise load of passengers can be cleared in less than three hours, checks are never glossed over.
The ICA spokesman said: "Even as we give speed and efficiency to cruise travellers, ICA places paramount importance on our security standards, which cannot be compromised."