I think about twenty yards away, I was using my Nikkor 80-400 and zooming in and out between various seals and the aircraft on the range. Exif data on the files show these were taken at 240mm. The seals are laid all over the place from a distance of less than a yard to a couple of hundred yards. If you havent been there I definately recommend a vist. Its free, the seals are wild, and they are here until late December.