You begin your journey trapped in a pocket of air in the lower corner of the sky aquarium. The sky aquarium is a small place, a place where one tree grows a few meters away and where the constant press of water makes breathing difficult.
What makes this map hard is the relative lack of resources. At first glance there are no animals, no grasses, no wheat farms, no mushrooms, not a whole lot of food of any kind in fact. Small pockets of ore do exist, but they are not easily found and the player will have to create ways to hold back the waters in order to harvest their bounty.
Although this is a tiny map, I found it to be one of the more enjoyable sky survival maps thus far, perhaps because exploring the small reaches of this little map took an awful lot of engineering, and when I found those precious deposits, I felt a glow of achievement difficult to attain in a world where one takes air for granted.