It's pretty Grizzly. Don't get me wrong, my 8yo loves it, my whole family loves it, but we tend to get soaking wet when we ride it, and there are some drops and rough water that can be scary for some kids. I know that my son was frightened by a similar--but somewhat tamer--ride when he was four. I guess it really depends on your sons. Honestly, I'm amazed that your sons will be tall enough! My daughter didn't hit 42 inches until she was almost six.
The belt is just a strap across the lap, that's it, and sometimes the straps won't tighten enough to hold a small child securely. The water can--but doesn't always--come up over the back of the seats. You don't always get soaked, but I have the good fortune and talent to walk away drenched every time.

Experience has taught us that riding this ride is not recommended right before Soarin' unless you want to turn blue.

Also, tennis shoes and socks will make your feet turn into painful prunes if you wear them on this ride.
If you still want to get soaking wet, and feel that this ride is too scary, you can go to Bountiful Valley Farm, which is a water play area. Again, no tennies and socks, you will regret it. They CM's will ask that you wear shoes, though, so
crocs or sandals seem like a good idea. If you go to Bountiful Valley Farm, experience has taught us that going to see It's Tough to Be a Bug right after is (again) not a good idea. Unless you like the color blue.
