She's done it! Dd can swim ON TOP of the water and she's delighted with herself. Swimming underwater was fun, but she clearly sensed she was missing stuff that was going on over her head - which is after all, the perennial problem for the younger child.
Of course, there are advantages in being the youngest. She is so utterly determined to do stuff in order that she is able to join in, that she gets there pdq. There are the occasional bouts of frustration but almost no real anxiety. Total, unwavering belief in her capacity to do things...it is peculiar this child of mine.