Unfortunately, it can be in the water badly read the temperature. Ok, you can it to yes take out - only a thermometer should be "usable" in the water in my opinion.
But what was really stupid: our little one had the thermometer exactly once in the hand and has pushed it when playing against the tub rim. It is immediately broke down.
Conclusion:
Inexpensive, optically really nice to use limited - and not for children.