As a former swim coach and lifeguard...
The best thing you can do for your kids is teach them how to swim but most importantly how to float and if they're in distress what to do.
I'm the mom at the edge of the pool. Still at 7 and 9 and my kids are really string swimmers but that doesn't matter. Anything can happen to any level of swimmer.
I hate rafts and floats in the pool. Too many is a disaster waiting to happen. Too many kids swimming underneath and sitting on top. You can get trapped under there so easily.
I am a nervous mom too when it comes to the water. We use puddle jumpers in the pool since I have 3 kids and 2 hands. But when we go to the beach I won't let the kids use them because my fear is (and it was confirmed by a lifeguard at the beach) the puddle jumper would just make them get swept out by the undertow faster than I can swim/catch them. That said, I also don't go to the beach without at least one more adult so there are more hands to help ;)
At the beach. Same. You need a vest or no water above knees. My kids know not to go far and I'm still right there but one big wave and you're all out in the tide. Terrifying.
I don't love the ocean. Lol