It's not even twenty miles, and it seems as if Forlond (which should be to the right in the image) and Harlond (to the left) are connected to Mithlond, like an agglomeration. Perhaps this isn't the entire gulf. However, maps like the one in the link don't show any such landscape on them, except for the last two peninsulae of Lindon, which I identify in the image as those with the exceptional hills that look similar to each other. The entire Gondorean navy could easily fill the gulf and perhaps more ships anchored outside it during the battle against Angmar.
So the question is, how big is the Gulf of Lune actually; are there any numbers? If it really spans more than two hundred miles far (i.e. the above image isn't the entire gulf), where in the maps do we find the landscape portrayed above? Or if the above landscape isn't featured on the maps, then why not? Does the image above include Har- and Forlond?