Thanks for the advice everyone, I knew about resubmitting turns. I do not think anyone was trying to call out Mindmaker as much as point out that there was still a turn on submitted so I can attempt to correct for the mistake.
Unfortunately I made a mistake on turn 3, which is why looking at turn 4 let me realize I had made a turn 3 mistake. So – little too late to resubmit!
My correctly understands sailing led to cross only one see province? Somehow I did not know that, but that makes it far less powerful and more in line with what what I would expect for its cost. Remember, provinces on connected by a continuous chain to some kind of Fort do not provide income. Thus using sailors to grade across the channel or the sea is fine, attempting to conquer land means you have to use sailing commanders to take the land and then hold it – without mages – for long enough to put up a fort on that side. Establishing a beachhead long enough to turn it into a fortress was difficult in the real world and I am had there is some difficulty doing that in this world. Of course, once you have flying/teleported mages all bets are off!
About the island being unconnected – I think that is a problem and should be fixed, but should be fixed mid-game? Should there be a warning of a certain number of turns? Players in that area may have done initial expansion and strategies based on that island being unconnected, or it may be a non-issue. However, without asking those players to self identify and give up strategic information it would be difficult to decide. I could see something like, "the sea seem to be lowering and by (some specific turn off in the future) it is expected that this connection would be available." That would give people time to readjust the strategy if the changes can happen 3, or perhaps 6, or more turns off. I think the ability to cut provinces off and thus their income is new to dominion for, and this map was made for dominion 3. So the ports in dominion 3 provided all the necessary connection between continents needed.