for this one, bb stays on the water. he or she may get cold. It's better if you hold him/ her and stay in the water for a while. Or choose the one surrounding the neck.
same here! my baby is 5mths old now and i want to take her swimming, but i don't know if the pool water would be too cold for her? would she get sick easily? my brother bought an inflatable pool (big enough for one baby only) for his daughter who's 4 months old. they pour in warm water so it's ok.