Floating tanks are good.  Flying Tanks is better.  We already have those. Harriers and Hornets.  I'm biased but IMO an up armored LAV would be tits.  A company of LAV has destructive powers even Odin would envy.  But yeah. A floatin tank would be cool. Amtracs are creepy cool though. You know you're underwater riding in them. RPGs chew em up unfortunatly.