I appreciate what you're saying; but I'm not suggesting naturalizing 1/2 the space in the park.
I'm looking at space that generally won't serve any other function; and/or is required for ecological reasons, flood management reasons, or erosion control.
Portions of the Islands are under serious threat from the above, including damage to rare habitats such as sand dunes.
As examples, this mowed edge along Lakeshore Avenue on the Islands amounts to several acres of land in total, but adds nothing.
On a car-free island the road is sufficient space for pedestrians and cyclists, and that adjacent space isn't really usable for picnics or the like:
View attachment 306481
Likewise, the absence of shoreline naturalization to a reasonable depth (not less than 10M, ideally more like 30M) leads to real risks of shoreline erosion:
View attachment 306489
There are also low-lying areas that are prone to flooding.
View attachment 306490
These will not be addressed by vastly increasing the height of this land. The paths/roads will be elevated, but not the entire space. Among the more practical ways to address this would be to consider regrading the existing land, and deepening the water-holding area in one location (increasing flood storage capacity); while berming some of the edges to guide the water where you want it to go. This allows for creating sustainably dry, usable land, while creating a wetland on the balance of the space, which could see a boardwalk and/or outlooks included to make it something to visit while on the Islands.
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Worth noting, I'm not advocating all nature.
I've suggested widening Avenue of the Islands and splitting it into a dedicated bike trail and grand pedestrian path.
I also favour more varied and high quality food concessions.
Bikeshare on the Islands
And suggested a destination Children's playground as well.
I also favour discussions w/the Yacht Clubs to see if paths can be arranged through their dedicated Islands (via bridges, high enough to allow watercraft underneath) to create greater connectivity throughout the Islands.
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I just think its important that the Islands be what they are; an escape from the City, not an escape to even more City.