couple of things that will help you along here.
People (for the most part) are naturally buoyant in salt water and this will help, espeically small children.
2. There are plenty of places to stand up and just rest for a minute in the snorkel lagoon.(mostly in the beginning)
3. The snorkel area is separated by a rope barrier from the swim part of the laggoon. It also begins and ends at the beach.
4. There are 2 different courses. A begginers and a advanced. Total length is about 2000 feet give or take for each. There are different colored balls that mark all of the mand made objects, such as the Mikey and Minnie statues, 20k sub etc.
You are required to wear a snorkel vest. The vests are designed that with a little bit of air, they will force you into a head up, and back position. They will also keep you afloat.
When we went with our kids for the first time, an 8 year old and a 7 year old,we had no problems. My 7 year old, I told we are going to that bouy there. TUrned around and cheked on my wife and son, and looked at my daughter and she was halfway there.
Since you are snorkeling, and idea is to put an adult between each child, and you can all go at the sane time. Chances are though, that at least 1, if not all 3 will have no problems.
The 1 thing I would do though, is to make sure that everyones gear fits properly. If not its going to be a long swim.
1. Take the mask that you like, and place the strap over the front lens. Make sure all of you hair, or your childs hair is out of the way. Place the mask over your eyes and nose, and inhale. and hold the mask against your face. If you feel air moving, or while inhaling, it feels like the mask is going to fall off, try a different mask.
2. Once you have found a mask that fits and you like, try out a snorkel. Most snorkels today, come with purge valves in them. Try and stay away from the 1 piece snorkels. Find one that the pieces can be changed, especially mouthpieces. Now, place the mask back over your eyes and nose, inhale again, and place the snorkel in your mouth. If it leaks, try repositionong the mask. If ti still leaks, chances are good the muoth piece is too big. (mouth pieces are about 5 dollars.) change it out with a smaller mouth piece.
Heres the 2 most important things.
1. Last time I looked, the grouper have stopped issuing tickets for fashion. If it doenst match color wise, no big deal. The Barracuda wont laugh either.
2. Take your mask, and scrub the inside lenses with straigh toothpaste. Not the gel, or 1 that has ides added, or any type of whitening. Rinse out the mask, and do it again. When you think your done, do it 1 more time. All masks have a coating on them from when they are made. You need to get this coating off before anytype of defog will work. just before you go in the water, put your defog in. Some of the more common types of defog are, saliva, 500psi, defog, or even a 50/50 mix of tearless baby shampoo and water. Put it in a smal spray bottle and your good to go.
Fins.
No matter what type of fin you select, try it on. It should be snug, and if open, your heel should sit out of the pocket. Dont stand on them.(any fin) they are not designed to walk in. In a seated position, lift up your fin. rock it back and forth and see if the fin moves. If it does, try a smaller size. If not, you may need a sock, or boot.
When you enter the water, carry the fins to the water, until you are waist deep. Then put your fins on. Unless you like falling, then put them on on land, and make sure someone gets it on video.
1 Other thing. dont put too much air into the snorkel vest(they are free on CC). They are designed to put you into a faceup on your back position, whenthey are inflated. I dont know how many people Ive seen fight the vest the whole time they are in the water. If you are concerned with someones swimming ability, place a little bit of air in it. Dont fill it. Salt water is naturaly bouyant, and will help you float. Dont fight the current. It will win. Work with it. If you need to go against it, aim to 1 side of where you are going. Go to the farthest point, and let the current push you back. Youll be much happier.