First holiday with toddler

Next week we’re going on our first family holiday since our youngest was born. It’ll be fairly hot and sunny and well likely be spending a lot of time in the pool or at the beach; what kind of swimwear would be best for my 2 year old son? And also what’s best for floatation; arm bands, inflatable ring, float jacket? I was gonna just put him in his usual swim shorts with some inflatable arm bands but after a few comments from people I’m starting worry!

Thanks!