Another from 2019 which I waited a long time to get.
The Great Crested Grebes are often seen waving there heads as a greeting but when they are ready to pair up for mating, they will dive to the bottom to get some weed on their heads. Then they swim towards each other and rise up from the water chest to chest while intertwining their necks.
Many times they will abort as one of them is not receptive but when it does happen, it lasts for about three or four seconds and the amount of energy they use to keep their bodies out of the water is amazing so is a case of being constantly ready with the camera