ZHMY(Big Shark) - Diving Toy Pool Glide Shark Throw Torpedo Underwater, Pool Shark (Big Shark)

Why are you supposed to be age 36 and up to use this? Is there some sort of danger that isn’t evident to the naked eye?

Do they sink to the bottom after the dive, if no one retrieves them, or do they float on top of the pool water?

How long are they?