"Too sore to sit down." Brisbane teen Brianna Thompson swam across the English Channel. Twice.

Since she was just 13 years old, Brianna Thompson has dreamed of swimming the English Channel.

Last year, after months of training, the 17-year-old from Brisbane completed a single crossing of the Channel in incredibly rough weather conditions.

But this year, the Aussie teen attempted an even more difficult feat – a two-way crossing of the English Channel.

Earlier this week, under the guide of English Channel world record holder Trent Grimsey, Brianna became the second youngest person in history to complete the 68 kilometre double crossing.

We got our P&O ferry shot!!! ???????????? @GrimseysSwimfit @TaraDiversi @RedTopSwim @CSAswimmers pic.twitter.com/IZ9uzusIog

— Tim Denyer (@CoachTimSwim) July 9, 2019

Beginning the swim at Samphire Hoe on England’s south east coast at approximately 4am (11:35am Brisbane time), Brianna reached Le Gris Niz, France around midnight Brisbane time, before beginning the return trip back to England, which she eventually reached in the dark hours of the morning.

Overall, Brianna swam for a total of 22 hours and 37 minutes, with four half-hour feeds.

With water temperatures of just 16 degrees, the 17-year-old faced the threat of hypothermia while crossing the Channel. Thankfully, however, warm drinks along the way helped fight off the cold.

“As my body began to shut down towards the end, I could feel the cold creeping in to my body,” Brianna said.

“But then the adrenaline of finishing kicked in the closer I got and I knew I was safe from hypothermia.”

BRIANNA THOMPSON is a 2-WAY English Channel swimmer!!! 11:05 + 11:32 = 22:37 Boom!!! ???????????????? @CSAswimmers @TaraDiversi @GrimseysSwimfit @TaraDiversi pic.twitter.com/kWLJJIAIyO

— Tim Denyer (@CoachTimSwim) July 10, 2019

Along the way, Brianna also had to battle everything from severe leg cramps, a swelling throat and dozens of jellyfish stings, including one on her face.

“The worst part were all the jellyfish stings and massive piles of floating seaweed. When you are swimming for hours, these things give you a big fright. The jellyfish hurt for ages. They really aren’t fun,” Brianna explained.

Twenty hours into Brianna’s swim, her coach Tim Denyer tweeted: “Well into English inshore waters now. Significant leg cramps and mental anguish.”

“Lots of tears. But she’s pushing on now with a renewed attitude and working hard to hit the coast.”

20hrs in. Well into English Inshore Waters now. Significant leg cramps and mental anguish. Lots of tears ???? But she’s pushing on now with a renewed attitude and working hard to hit the coast @CSAswimmers @TaraDiversi @GrimseysSwimfit @RedTopSwim pic.twitter.com/W77t2qmCFX

— Tim Denyer (@CoachTimSwim) July 9, 2019

For 18 years after completing the swim, Brianna was too sore to sleep or even sit in a chair.

“I am too sore to sit in a chair. And when I eventually do, I am too sore to get back up,” she said.

“I am really craving a pizza but almost 24 hours has left me with a very sore and swollen throat. I’m in agony. I could feel my throat swelling up during my swim and each feed became more painful,” she added.

“I’m still two or three days away from that pizza but finally I can talk! It will be days before I can lift my arms above my head!”

Brianna seems happier now she’s turned and is on the return leg home. Boat is staying nicely in gear and the sun has come out ???? @GrimseysSwimfit @TaraDiversi @RedTopSwim @CSAswimmers pic.twitter.com/gTZ6Cg77cs

— Tim Denyer (@CoachTimSwim) July 9, 2019

Brianna is the 21st person in history to have completed the English Channel Double Crossing.

She is also the youngest person to have completed three crossings in 12 months following her single English Channel Crossing in September 2018.

“I didn’t set out to enter the record books, I just wanted to see how far I could go. I can honestly say it took everything I had to get to the end,” Brianna said.

“I always knew I would make because I did everything my coach said. He holds the World Record for the Channel so who am I to argue with him.”

You can find out more about Brianna’s English Channel swim on her Facebook page.