Theisn't even out yet, but already companies are announcing accessories for it, including cases designed to toughen it up.
Italy-based ActionProof has launched an Indiegogo campaign for "The Bumper," which it bills as the first shock absorber for the Apple Watch, giving it "extra superpowers."
We have no idea how it'll feel on the Watch, but if you're looking at the entry-level 42mm Apple Watch Sport ($399, AU$579 and £339), which features a lighter-weight aluminum case and Gorilla Glass screen, not one made of Sapphire (you have to step up to steel-case Apple Watch, which starts at $549/AU$799/£479, to get Sapphire), it might be good idea to look into The Bumper.
In an early-bird special, you can pre-order a plain black Bumper for $20, worldwide shipping included (its regular price will be $35). Alas, the case is currently slated to be available only for the 42mm Apple Watch, not the smaller 38mm version.
ActionProof has promised it will ship The Bumper in May, though there's no guarantee it will. By then we do expect other cases to appear from other companies. Perhaps we'll even see a case someday that makes the Apple Watch fully waterproof. That would be nice.