Is there a 100% waterproof IP rating?

No device can be guaranteed to remain completely water-resistant under all conditions indefinitely. However, in terms of IP ratings, certain standards indicate a high level of water resistance that qualifies a device to be considered effectively waterproof for particular conditions.  

IP67 allows for temporary submersion in water up to 1 meter for 30 minutes,  
IP68 protects against water up to 1 meter deep for extended periods, as specified by the manufacturer.   
IP69K, however, withstands high-pressure, high-temperature water jets, offering superior protection in extremely harsh environments.   
IP68 and IP69K are some of the best standards for water resistance. Devices with these ratings can be used underwater and withstand rigorous washdown procedures.    

It is important to consider not only the IP rating but also the type of sealing used, particularly for functions critical to safety.