YESSS YESSS
Left-bottom image, make ship be able to sail in that "little lake" in the middle.
For example, the ylands formation we already have, with the 5 small ylands in a group, my ship with origial hull will not sail in the middle of all ylands, only in some parts.
Yes, to travel between ylands i use a boat, but sometimes i want sail out to go explore and i want to be able to sail trought these small lakes to the ocean and start my expedition to go pillage some...