A little old school 80's slasher, a little post-Scream modern slasher, mix, add water and you get something like this killer-in-a-mask slasher. Very formula in a slightly different setting, lots of pretty teens, this time at a large indoor pool (hence the title) are being stalked. And this time an English language German movie filmed in the Czech Republic with an international cast of young pretty actors.
It was played straight, and built some nice tension which was nice like the slasher pics of old A good amount of blood, but light on the gore and only one very brief flash of nudity are the bad traits it has inherited from the post-Scream generation of slashers.
A sequel is coming up. I assume that will also be set at a pool (since it being called Pool 2), or perhaps the same pool. Add a little gore and T&A next time around folks.
If you enjoy competently made slasher films that don't stray too much from the formula then you should find this a pleasant 90 minute diversion.