Swimming is good for you
More than any other activity it develops flexibility, stamina & strength in equal measure.
Safety issues
There are dangers associated with water.
Bare in mind their age & general fitness.
What’s their confidence like?
Some swimmers will be familiar with the pool environment, others not. Some may have older siblings & parents who swim, which may help them feel ok about being poolside … whilst others may find the entire thing new & daunting.