Pair of great crested grebes on Doxey Marsh’s Boundary Flash.
They would swim in parallel, some distance apart, then gradually come closer together. They would now swim in parallel, close together. Sometimes they would put their heads close together. One or other (or both) would dip their heads under the water, though they did not bring up any weed to present to the other bird. After a little while they moved further apart, and began to repeat the cycle.