Amazing experience which the tour company managed in a simple no frills way. They provide a brief overview to start, provide shorty wetsuits (recommended- you just float and don't move much), keep your gear safe and dry, and rent "GoPro" cameras if you don't have your own underwater camera. They take kids to 7 year olds, though our kids weren't brave enough to try it. The Mantas are large and they come close so your child should be comfortable floating in the water and have a solid amount of bravery.
I want to give out a special shout out to our crew Captain Laruen and her crew of Bailey, Morgan, and Ana. They kept us safe on the night a Tiger Shark was spotted and the trip had to be cancelled (full refund or rebooking was offered). I also give a special shout out to our crew the following night Captain Brenden and his crew Jessica, Marlene, Taylor, and Ana. They provided safety and knowledge through out the experience!