I don't think I have ever seen this amphibious ATV before. It is called the Balrog and according to their site it has been in production since 1989. While it looks like it is mainly geared towards the commercial market it could just as easily be used for recreation. It is a hydraulically driven 8x8 (two pumps) with a 66 HP Kubota Diesel, a 4 speed and a single joystick for controls. 
Here's the link to their site:
Balrog Amphibious ATV

Here's the link to their site:
Balrog Amphibious ATV
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