Yes, Dynamo goes swimming daily in summer. Collar is waterproof. All dogtra collars are waterproof, and I'm guessing the same goes for tri-tronics too. Transmitters (the thing you hold, or wear on a lanyard around your neck) are 'water-resistant' in the low end models. That means, if your dog shakes water at you, it's fine. If it starts raining, it's fine, if it's misty, it's fine, but you definitely do not jump in the water and go swimming with your dog while wearing the transmitter. I put mine away if it's raining hard (sometimes just baggy it). In an ordinary rain, I put it under my shirt. I don't regret buying the 'water-resistant' as it rarely gets so wet out that I need to worry.