There is a distinct pattern of bubbles that mark the trail of a submerged Otter. They burst at the waters surface and mark the route of an agile mammal moving at some speed. This evenings were typical; swimming at what must have been no more than say a foot’s depth, where the River Mermaid joins the Bure, the line of bubbles was a like row of silver coins – each a few inches apart in a curving trail under the footbridge. The Otter kept submerged until the safety of the overhanging willow where it invisibly surfaced before diving to the sanctuary of the deeper waters of the Bure. We waited to see if would return, perhaps racked with the supposed curiosity of mammals of this type, but it had obviously seen enough of us and had retired out if sight.