Bright red watch is hard to lose, which is handy when you're competing!
Let's face it, no matter how good of a surfer you are, you're bound to wipe out at least once in every race. And when that happens, if you don't have your watch strapped on tight, it might slip off your wrist. Knowing this, Casio coloured the GLX5600F-4 a bright red, making it very easy to spot.
Seeing as the watch may be under water quite a bit, 100m was never going to be enough, and so Casio made sure their GLX watches were all resistant to 200m of water pressure, so even if your watch falls off your wrist, when you find it there's a good chance it'll still be working perfectly.
As a watch for surfers, the main feature for this watch is a tide graph combined with a moon graph/phase indicator. This gives you an accurate reading of not only how the tides are on the day you look at it, but if you change the date, the graph changes with it, giving you a heads up when preparing for your race.