According to their teachers, Gus has "a great freestyle stroke, has accomplished deep water treading / floating, and long-distance freestyle and backstroke swimming. Niko can do an "elementary backstroke" and has mastered all the rudimentary skills for his level.
All their hard work is not without its rewards. On the last day of class, not only is the free swim time extended, but it includes (supervised) access to the water slide. As you can see, the boys took full advantage!