Reddit mentions of Casio Men's MRW200H-1BV Black Resin Dive Watch

I think that Casio have a reputation for making very rugged, waterproof and inexpensive watches.

Casio's G-shock brand has become iconic because of its modern military associations but they do cheaper water resistant watches that certainly look pretty solid. I used to have a resin encased casio as a kid and it was waterproof and very tough.

Here's a good looking one for less than $20