If I'm not mistaken, this is how the Flippers work in the GB Zelda Games. If you go into Shallow Water, you can swim in it, but not dive. So, what I'm thinking is a Quest rule, "Flippers work in Shallow Water." When it is triggered on, if you have the flippers, you can swim through the Shallow Water, but you can't dive (because it's shallow).

Thoughts?

Man, I sound like DN when I write that..o_O