I made this Maproulette challenge, and I am commenting here because SomeoneElse asked me to clarify the instructions.

Trying to figure out what happened here. The challenge shows users islands that are likely to be submerged, because someone drew a way inside a water body, tagged it place=island, and didn't make it a member of the surrounding water body.

https://www.openstreetmap.org/way/692587227 is a bit odd: it doesn't need to be an 'inner' to the surrounding water body because it's between two water bodies (https://www.openstreetmap.org/way/854475224 and https://www.openstreetmap.org/way/854475223), so adding it to the MP will make it invalid.

I can add this scenario to the instructions, asking mappers to leave such examples alone.

However, in this case it looks like a bit more went wrong: The place=islet tag should normally remain on the island, but in this case it was removed from the island (https://osmlab.github.io/osm-deep-history/#/way/692587227) and added to the water multipolygon (https://osmlab.github.io/osm-deep-history/#/way/692587227).
@huozhe: do you think there is anything else that could be improved about the instructions to make them better?