This is a very nice MOC!
The overall building is nicely layout. The small hill is really very nice, and I find that the yellow bricks, to illustrate a sandy beach. It certainly pass the message well across.
The steps, up to the hill, is done in a very neat manner. Perhaps, too neat and well arranged. It will be even better to add in moregrass or green by the side of the stairs to show a much messy look.
For your first attempt on your SNOT building. It's really very good by showing one of the Islander, hunting for fishes. Using the koi, is a smart move to illustrate the fish jumping out of the river.
The volcano looks abit small, and dormant. It looks like a fire pond. I am not saying it does not look nice. In fact, I find it very well design, to punish trespassers, by forcing them to jump into hot larva.
Thanks for sharing.