Are AirTags waterproof?

I wouldn't. For AirTag water resistance information, see the following from AirTag - Apple

AirTag is splash, water, and dust resistant and was tested under controlled laboratory conditions with a rating of IP67 under IEC standard 60529 (maximum depth of 1 meter up to 30 minutes). Splash, water, and dust resistance are not permanent conditions and resistance might decrease as a result of normal wear. Refer to the Safety and Handling documentation for cleaning and drying instructions.

Akyelli wrote:

Lost sight of my kid in a giant and very crowded waterpark briefly. I would feel better if she had her AirTag on.

An AirTag is intended to be used for finding "things" - not people.

While an AirTag is splash resistant, it is not waterproof - and can be damaged if submerged. Consider that the quoted water resistance is only for static pressure - this being significantly less than will be experienced if it (or someone wearing it) falls into water.

Not withstanding the potential to be damaged by water ingress, the radio signal from the AirTag is completely blocked when in water.

AirTags are water-resistant but not waterproof, so avoid submerging them in water or exposing them to excessive moisture.

Have two air tags worked fine until both went in the water air tags in sealed “watches” but now they both don’t pick up any signal even a few feet away. Very disappointing

An addition to my earlier discussion about air tags being water proof.

After being under water for a while (child in the pool) the air tags did not work but after drying them out they returned to normal

Im taking my son to a large water/ and would like to put one on his life jacket. I will be right next to him but at places life that you can never be to safe.

I feel like its a odd question but their are a few reasonable answers

Just curious. What would your child have that you would have an AirTag attached to when they would go swimming?

Lost sight of my kid in a giant and very crowded waterpark briefly. I would feel better if she had her AirTag on.

All discussions of water resistance aside …

… AirTags are simply a poor solution for tracking ANY moving object in near-real-time. (pets or people)

It’s NOT what they were designed to do.