Pack spare hats, bathers and rash vests that are going to keep them safe from the sun.
You don't want your kids sun burnt. That's no fun for anyone and is a fast way to ruin your trip.
Try to lead by example and slip, slop, slap yourself and don't forget to pack some sunglasses for the kids to protect their eyes from the UV.
It goes without saying, but sunscreen is super important.
Just pack enough to get you through a day or so if you can't get straight to the shops.
Remember different countries have different UV levels, so do some research before you travel on the sunscreen strength you should use.
Pack some aloe-vera to help soothe any sunburn. Just in case!
Warmer climates can attract insects, so make sure you have a travel-safe (non aerosol can) bug repellent that is safe for your kid's delicate skin.
Don't forget the pack some swim nappies.
Depending on where you are going, they may be a little harder to buy and you don't want to miss out on any important pool time.
Make sure you have had a few sessions at the pool with your kids prior to your trip.
Here you can sort out if you need to take any floating aids to ensure they stay safe. You don't want to get to your destination and them fear the water.