Waterproof Activity Tracker

Ok, so I've searched the message boards and looked at all the posts about the different fitness trackers and heart rate monitors. I've been considering either the fitbit Ultra or Flex or one of the Polar heart rate monitors or maybe even both. One of my slight problems with each of these though is that they are not approved for swimming. I love to swim and do laps and would love to be able to accurately track what I burn during my laps. Does anyone know of any waterproof trackers? Or even a band of some sort to make the non waterproof ones... well waterproof? Other suggestions would be awesome as well