The Queanbeyan formula one driver has hosted a team this year, which has included Olympic champion James Tomkins and other high profile sports people, and they have battled the elements in the seven-day competition.

The event has included gruelling stages of extreme sports, with mountain biking, white water rafting, kayaking and long hikes and treks through the Tasmanian wilderness.

Webber, who runs the event every year to raise money for charities The Mark Webber Challenge Foundation, The Leukaemia Foundation and The Save the Tasmanian Devil Appeal, was running in the top five before missing a crucial checkpoint with Tomkins.

Starting from the back of the field he has managed to peg back some teams, and remains just outside the top ten with the weekend still to race.

Webber was frustrated with his rafting experience on day four of the Challenge.

"We started a little shaky on the paddle.

"Our rudder wasn't down and ended up off the course a bit with some ground to make up."

The 450-kilometre event finishes on Sunday.