Families that go on vacation around a river, lake, water park, sea shore, etc. may think their children will jump right in and are surprised when Red Ribbon Jack or even, Purple Ribbon Emma, do not show off their skills in this different water right away.
Take heart because there are simple, supportive ways for your tribe to quickly enjoy the long planned fun time.
Remember that children pick up on how this new water looks, feels and perhaps smells different. Maybe they can't see bottom, or it is cooler than they are used to. Crashing waves sound loud or try to get their toes. There may be currents that unsteady them or fish that they can see (I was a young swimmer but fish scared me...still do!)
Before arriving at your destination talk with the children about how the water will look and feel different from a swim lesson swimming pool. Find photos if possible so they have a visual. I remember taking our three kids to Russian River and sketching how the river turned, and how maybe the currents would give you a ride. We explained how to swim at an angle to flow with the water. They didn't need to go straight to shore, in exactly the spot they wanted. My daughter Liesl can tell you that story when she jumped out of our canoe at the age of 3!
Take the first 10 minutes after getting to the water to review what the children already know skill wise. The children, especially the younger ones, need time to assimilate all the stimuli. If you have been sensitive to their hesitation and they balk after a reasonable time, gently carry them or hold their hand firmly and get them one step further into the water, keeping a positive, playful voice and attitude.
Do the 10 minute review every day. You can ask for suggestions from your teacher or the deck support person too. They can give 'homework' for the kind of water you visit and skill levels of your kids (http://www.swimlpb.com/classes/homework.html).
Lastly, whatever water you are around, please assign someone to be the designated "water watcher". This means they have been given a tangible item (we use a bracelet of some kind) and it means they will not use a phone, engage in conversation, or be distracted in anyway. Their sole job is to keep watch over the little whales in the pool. We have used the bracelet idea for Disneyland too when the crowds are big and children can get lost in the shuffle.
Everyone enjoys the water much more when water skills are good and everyone is more relaxed when a safety system is in place. Now go out and have a wonderful swimming summer!