The host-nation won three medals in the pool, a silver and two bronze, but the most precious metal eluded them. But that could all change on Thursday when the marathon swimming gets underway.
Britain's Keri-Anne Payne is the favourite to win the women's event, 10 kilometres inside the Serpentine, a recreational lake in Hyde Park that was constructed in 1730 and remains one of London's most iconic tourist destinations.
Payne won the silver medal in Beijing four years ago but has established herself as the woman to beat in London after winning the past two world championships.
"She's in good form and she's ready to go," said Mark Perry, the leader of the British team.
Despite her success, Payne is no sure thing.
Italy's Martina Grimaldi holds the European title and finished less than two seconds behind Payne at last year's world championships and Marianna Lymperta of Greece and Germany's Angela Maurer also loom as dangers in a wide open field.
Both the men's and women's marathon events are restricted to the top 25 competitors in the world.
They will each complete six loops of the lake, in around two hours, where they will share the murky water with geese, ducks and swans, and battle through thick weeds and poisonous algae that can cause severe skin rashes, eye irritation, vomiting and diarrhoea.
Marathon swimming was only introduced to the Olympics at Beijing but competitors this week could compete in front of one the biggest crowds at the Games because it is one of the few events that spectators can see for free.
Greece's Spyros Gianniotis won the men's world title in Shanghai last year, just ahead of Germany's Thomas Lurz, who also won bronze in Beijing.
"Everything is OK. The preparation was good," said Lurz.
"At the Olympic Games there are always some other swimmers that are good. All the other swimmers I respect them. I won't beat them easily."