We were on the Chesapeake Bay when this target showed up (during the day) coming straight at us at 25 knots. I'd pop up and look ahead but nothing. I'd go below and there it was, straight at us at 25. We were unable to avoid what we couldn't see coming at us at that speed so we just watched as it passed through us. I looked around and even up but 'nothing'. Didn't know what to think about it other than it could have been a flock of birds. Only problem was the sky was clear and I saw nothing.

It can get weird out there.