After the recent rain there four inches or so of water in the bottom of the small boat I use for lake maintenance. When I went to bail it out I discovered a large beetle swimming around in it.
The creature was probably the biggest beetle I had ever seen, around 35mm long, and was clearly fully at home in the water as I could only think that it had come on board swept up in the weed I had been clearing from the pond earlier in the week.
As I bailed and the water slopped around in the boat it did seem to want to climb out of the way of the surging waves that raced up and down the boat, but once engulfed would happily swim. In the water it's main legs could be seen to have feathering on them that clearly were helpful for both propulsion and steering.
The closest I could get to identifying the breed on iSpot
was Colymbetes Fuscus, but unusually, no one has responded confirming my identification.