The Munda Biddi is a purpose built mountain bike trail currently stretching from Mundaring to Albany south of Perth in Western Australia.

Note - Andy Hewat completed the trail when it was at 550km in length (prior to the extension) and this has now been added as a variation for record keeping.

The Hillary Trail, named after Sir Ed Hillary, for whom this was a special place, is 75km in length and features 3,300m of vertical ascent. It is mostly technical single-track running/walking through some stunning bush and coastal scenery.

Note that an 80km race is held annually on the Hillary Trail.  The race adds 5km to the route, and also skips one section of the actual Hillary Trail which is in a scientific reserve where events are not allowed:

The Great Ocean Walk is a walking trail located on Victoria's south-west coast in Australia, traversing several areas of historical and cultural significance.

The 56km Milford Track, in New Zealand's Fiordlands, is surely one of the most famous hikes in the world.  But, perhaps strangely, we are not aware of much FKT activity on this route.  Perhaps locals know of some fast times?