The Princeton Tec Apex is NOT suitable for swimming. While doing field research in Panama this past summer, I tried using it while snorkeling at night. I figured that if it was "waterproof to 1m for 30 minutes", then it should work just fine if I stayed at the surface.
It worked very well for a 30 minute swim, and I never submerged it more than 6 inches underwater. However, the battery case flooded and a lot of condensation appeared within the lamp (although it never stopped working).
To save it, I placed it in a low temperature oven we used for drying sponge specimens for a day and the condensation finally disappeared.
It still works and I use it regularly for caving, but I now know that PT's claims about being waterproof are a bunch of hogwash.
Their "waterproof" claim means that it probably won't die if it rains while you are using it.