As Benjamin is saying, it seems there are endless methods for friction fitting the knife to sheath... but a knife that size, realistically, would not be carried in a friction fit sheath. Mick is stumbling around in the bush, jumping over this and that, stabbing crocodiles and such, and that big bowie-style blade just wouldn;t stay in there by friction alone....at least not as much as you'd want to trust it.

I wear a small Benchmade around my neck in a Kydex sheath. It stays put just fine, but the knife only weighs about 2.5 ounces. Even though I haven;t seen the movie in awhile, Crocodile Dundee's knife probably weighed from 3/4 to 1-1/4 pounds. He'd need a retaining strap or a beefy roller pin/spring setup like Benjamin was describing.

HOWEVER! A leather vertical-carry belt sheath would do just fine even with some jumping around and a few croc stabbings... as long as the leather was molded to fit the knife just right.