However, his bad day got a lot better when police divers who were out training offered to help retrieve the loot, reports ITV News.
Philippa Bungard, from Bristol Community Ferries, told the Bristol Post: "We're not exactly sure how much is in there, it was certainly hundreds of pounds – it would have been maybe £200, as much as £300, it happened about lunchtime.
"The staff member who dropped it was extremely apologetic. It wasn't his fault though, the strap actually snapped on his money belt just as he was getting on and off the ferry at the bottom of Cascade Steps. It went into the water, and he was mortified."
Bristol Ferry shared an Facebook update about the incident, in which it revealed that divers in fact retrieved at least £460 from the water.
The new plastic £5 notes passed the waterproof test with flying colours and were still instantly useable, while the £10, £20 and old £5 notes needed a bit of air-drying.
Bristol Ferries will be donating the money to a charity of the police divers' choice. It was decided the money would be split between The Marmalade Trust and the Julian Trust, which help lonely, isolated and homeless people in Bristol.
10 best boatels around Europe
10 best boatels around Europe
Sleeps 4, from £134/night
Amsterdam is famous for its canals so why not make your visit even more authentic by living life on the water and staying in the Houseboat Suite Westertoren. This boat sleeps four and can be found right in the heart of the city, with views of the famous Anne Frank house and beautiful Westerkerk.
Sleeps 4, from £150/night
These two houseboats can be found in the heart of east London at Gainsborough Wharf. This is the perfect location for exploring the East End with Colombia Road flower market and Brick Lane both close by.
Sleeps 2, from £143/night
Salt and Sill is Sweden's first floating hotel and the property offers guests the chance to explore the beautiful Klädesholmen Island and Bohuslän Archipelago. The boatel is just 45 minutes drive from Gothenburg and there's even a seaside restaurant for guests to enjoy.
Sleeps 6 + 3 children, from £198/night
The Harbour Houseboat is moored in the scenic Bembridge Harbour with stunning sea views throughout. The boat is surprisingly spacious and is located just minutes from the village and beaches.
Sleeps 6, from £143/night
Although Larkspur is moored within walking distance of the city of Bath, you can take the opportunity while on board to explore the area on the Kennet and Avon Canal.The boat sleeps six and for those wanting to hit the water, you'll be taught how to handle and steer the boat before you leave.
Sleeps 2-8, from £27/night
These floating homes may not look like your classic houseboat but that doesn't mean they're missing any of the essentials. These quirky looking water properties boast terraces with views right over Lake Jamno. While some of the HT Houseboats are static, others are actually boats that can sail.
Sleeps 4 (2 adults and 2 children), from £176/night
If you fancy taking a unique opportunity while visiting Berlin why not try out the Modern Houseboat. With one side of the houseboat made almost entirely from glass, expect spectacular views of the water and surrounding area.
Sleeps 2, from £167/night
The Lilla Marras Reddingsboot is a former lifeboat that has been restored to make way for visitors. Guests can even hire their own private captain who will take you out on the water and demonstrate the boat's abilities.
Sleeps 4, from £79/night
Just a short walk from Sheffield's popular city attractions is where you can find this pair of stunning houseboats. The Houseboat Hotels. The 10-foot wide boats are surprisingly spacious and fully equipped with everything you need for a happy stay on the water.
Sleeps 8, from £252/night
This impressive property boasts four bedrooms and offers visitors the chance to relax while still in the heart of busy Paris. Devolu has a split-level deck, a terrace and even an ensuite bathroom.