Have you actually seen how deep 600mm is when you're driving in it?
Without a snorkel the danger is you'll suck water into your injun & kill it big time. Also if your axles are hot they could suck water in through the breathers. Your gearbox & transfer box have breathers that can suck water in too unless you fit extended breather hoses running at least as high as the top of your injun bay.
When you drive in water you aim to create a bow wave of water in front of you. This creates a lower area of water under your injun and most of the length of the vehicle. Get it wrong, drive too fast or drive into water too deep & this will break over your bonnet. With a wading kit fitted, no problem, without you could do serious damage.
Also, unless you've waded the water yourself (or got someone else to do it - Eh Adz?) you may find potholes which could cause you problems or cause a stall.........then you've got water flowing up your eggsauced too!
It's better to have the kit, or take it easy & don't push your luck...........spesh if you're wading/fording on your own!