Career He finished 12th in the middle distance and 6th in the sprint distance at the 2004 world championships.
Achievements He received a silver medal in the relay event at the 2004 World Ski Orienteering Championships in Östersund, together with Øystein Kvaal Østerbø, Tommy Olsen and Anders Hauge. He also won a silver medal at the 2010 Winter Military World Games. Tonna is a double national champion in ski orienteering.