Thousands of pounds' worth of new Huawei Watch GT 2s were up for grabs, but only for those brave enough to dive underneath the Dock water.
The shop was part submerged underwater and its shopkeeper dropped the watches into a chute that released them half a metre underwater.
Each watch, worth £199, was given away on a first come, first submerge basis.
People travelled from as far as Bournemouth, Southampton and Surrey to get their hands on a new watch.
Including Arkadiusz Zatorski, who was first in the queue. He said: "I was queuing since 6am so had six hours to psyche myself up to take a dip in the dock water. I'm a keen swimmer but only in the summer months usually."
Justin Costello, director of marketing, Huawei UK and Ireland said: "With its underwater credentials on top of all of the other sports data and technology it provides, it’s great to be able to show first hand just how good the watch is."
Mischief PR developed the idea. Andy Garner, junior creative director at the agency, said they wanted to add some emotion and tension to the launch.
"That’s where the Dive-Thru was born. The watch is brilliant for open water swimming so it made perfect sense, to provide an extra challenge to the public, consumers were invited to dive into the dock to get their hands (or wrists) on the new product.
"Huawei’s ‘Make It Possible’ positioning means that we approach every brief in the same way. Nothing is off the cards."