I always assume that any device can be circumvented. In this particular instance, I'm pretty sure some clever thief will figure out a way. Maybe move it oh-so carefully so the alarm doesn't sound, or perhaps stuff it into a large cooler filled with soundproofing, or figure out a way to disable the alarm (micro EMP?)

Your best bet is to put it into the safe at the hotel. If they don't have one or it's suspicious, see if a local bank will rent a SDB for the length of your trip. I won't ever again leave my wallet away from my person on a beach. A small Dry-bag ziplock is plenty to keep it safe. Strap that to the inside pocket of my swim trunks and I'm going out to sea! For women, I'm not sure if wearing a 2-piece or 1-piece, but if wearing trunks for bottoms, the same thing could apply.