As you can see I was bring up the rear in this group. I chickened out when it came to my turn to jump in the water. However, I did follow the group along the river bank.
It seems the little ones were being taught to dive for food. It was fascinating to watch 15 babies dive under the water and splash around. Then they would suddenly race across the water in a frenzy, flapping wings and reaching out with open mouths either to be ready to attack or reaching for food (not sure which).
It was very interesting to watch. I was only hissed at twice for getting too close or maybe they were making fun of me for not jumping in.