It looks like a whale making a huge splash in the shallow water just off the southern coast of Brownsea Island, Poole Harbour, England. I really don't know what it is...no trace of it exists in the BEV's or GM.
Very odd. The edge of the circle looks too smooth to be a splash. I live near whales and this isn't what they look like when they splash and they don't jump around in water that shallow. It throws a distinct shadow so it is not a satellite problem.
I suspect this is one of those rare maps that legitimately belong in the "unexplained" category rather than "info wanted."
I suspect this is one of those rare maps that legitimately belong in the "unexplained" category rather than "info wanted."