I am looking at getting a tough armor spigen case, and I hear the Watch can survive a shower. The spigen case seems to cover all but the Digital Crown. I am not comfortable even with rain on the watch unless I can swim with it. Assuming I use this case, about how far under water can I go if at all? And is there a better option?
A lot of people have had the same concern. I know someone tested this thoroughly. I wouldn't do what he did, but I wouldn't be so worried, though I can't say I've taken my Apple Watch into the shower yet.
You also asked about alternatives. Liquipel, which is a nano-coating that would protect your watch from water damage (they call it Watersafe), seems like a viable option. There are plenty of articles about it online. The only strange thing about it is that after late September, the articles seem to disappear. I haven't been able to find anything following that date.
Unfortunately, I couldn't find specs detailing how deep one would be able to go with either protection. Regardless, the Epik Watch from Lunatik seems like the most resistant or safe option at the moment, given their video and the lack of information on Liquipel. If Liquipel is still around, and you're willing to dish out the cash (it's a pricey combo to some extent with Liquipel for iPhone going for $60 and the Epik Watch going for $100), perhaps using both wouldn't be a bad idea.