I was looking up a link for someone and rediscovered the video today showing how to make tough and durable sandals from discarded tires. This style is well-known in Southeast Asia, particularly in poorer areas.
If you are interested in sandal-making, you can hardly go wrong with this design if you have access to old tires. I suggest watching the video if only for the remarkably sharp knife this maker is using. Using tire material is a little heavy but will truly last a lifetime. The straps fit purely by friction so they are continuously adjustable while the waterproofness of the material makes them perfect for the wetlands and jungle.
I understand this style was created in the 1940s when old tires became abundant and some creative shoemaker had a Eureka moment. There is also a short write-up on this style on the always interesting Huarache Blog if you are seeking more information about this shoe.
Another step toward self-sufficiency and off-grid knowledge for the Mayhem Shoe Collective.
Preindustrial Craftsmanship 
Holy crap! I don’t have the dullest knife on the block, but that was a whole different critter! Good find!
Beyond sharpness. Makes me feel inadequate. Reaching for a new level now.
looks like a self-made knife too.
Definitely.