Cassie Patten earned Britain's first medal of the 2007 World Championships, taking silver in the 10km open water event in Melbourne.
Patten (right) took silver after a gruelling race
The tough course saw all 42 swimmers get stung by jellyfish and several had to be rescued from the water.
The Briton took the lead on the final of the four laps but was pipped in an exciting finish by Larisa Ilchenko.
Patten, 20, finished in two hours, three minutes and 58.9 seconds, just over a second behind the Russian.
"I'm feeling quite emotional at the moment but it's pure happiness," said Patten.
"I'm tired and very sore as I was stung a lot on my arms, legs and face - they even got me through my costume.
"The stings were very painful but I'd tried to concentrate on getting to the end and to be honest they helped to keep you alert as you're out there for such a long time."
It was the fourth day of the championships, which run until 1 April.