Interactiondesigner
I can see, that there is much more mapped than the first time when I opened this issue. 
But to me, there are still certain details missing. On this island are certain footpathes (e.g. a circle way around the island) which are still missing. Additional there are picnic sites, benches, roofs against rain, panorama spots etc. The island is not super huge but you can spend a lot of hours there and for somebody walking around there such informations are essential. 
Also on the lake itself is a ferry cruising, going from the main town to the island but also to other spots too. Those ferry lines should be added too to close this issue. 