The deep ponds and lakes are almost in the same natural state as after the Ice Age. Their water is clear and oxygen rich, containing a large amount of groundwater filtered by the eskers. There are plenty of amphipods and larvae for the fish to eat. Whitefish and pike have been a desired catch in Hossa for thousands of years.
There are also ponds lined by mires in Hossa. The stripes of the perches swimming in them are dark, and so is the spotted skin of the pikes.
Some of the larger flowing waters have been cleared for log floating. Still today, they provide living opportunities for species that thrive in flowing waters. The gravel and rocky bottoms of the flowing waters are particularly important for fish that spawn in flowing waters, such as the grayling and the brown trout.
The small water bodies are the least studied natural features in Hossa. There may still be surprises in the plant and animal species living in small streams, such as rare mosses, or small animals on the bottom of streams.
There are a large number of springs and spring-fed mires, which are treeless areas with a thin layer of peat, where the groundwater reaches the ground surface, but which do not have a clear eye of the spring. The spring-fed mires are located on lower slopes of wooded hills and eskers. They often remain unfrozen in winter. The oxygen-rich groundwater contributes to the diversity of the springs, spring-fed mires and small streams.