This year's championships near Alexandra began on Tuesday and finish tomorow. They have followed the South Island championships in Dunedin on April 21-23.
Event convener Joe Sherriff said people came from all around New Zealand and Australia to compete.
The event involves six courses and about 20 classes, for people aged from 12 to over 70.
Competitors have to make their way through the course using a compass and a map between their bike's handlebars.
The championships started with a test run on Tuesday and continued with a 7-8km sprint yesterday. The riders tackle a 25km long-distance race today and finish with a 15km middle-distance race tomorrow.
Sherriff said the Central Otago land made the event a good challenge for competitors.
``It's the fun of both riding a bike and navigating at the same time.
``These areas are particularly challenging, as it's open land, grazed heavily by rabbits, sheep and the occasional goat which means you can ride anywhere.
``Most mountain bike orienteering is in forests where you have to ride on tracks all the time, so this will be much more of a navigational challenge than most events.''
The most recent national championships were held in Rotorua. The last time they were in the South Island was in Hanmer in 2011.
Sherriff said placegetters could go on to international championships in Europe.
