Not to rain on your parade, but before you get an Open Water dive qualification you would be lucky if you got down more than 10 meters. 18 meters is the absolute maximum distance allowed with a PADI certification. Even dive instructors don't go down much past 25-30m for safety reasons, because it takes AGES to slowly resurface, otherwise you'll get the bends
For diving, do what divers do and get yourself a Seiko Monster. It won't matter, you'll have a dive computer anyway, watches during diving are just for fun for us watch-lovers