All Fi Devices are waterproof. The Fi Series 3+ is tested to the IP68 standard underwater. This means your dog can swim in salt, fresh, and chlorinated water. These devices can be submerged in water up to 1.5m deep for up to 30 minutes. Please note that we recommend cleaning your Fi device after swimming.
Additionally, the Series 3+ is tested to the IP66K standard, meaning a water jet can spray the device at 150PSI in a 1/4" stream for up to 3 minutes without causing damage.