Wymięklizna Reserve was created in 1996, it covers 63 hectares of forests with rich undergrowth species, wildlife refuge to the south from the road Sobienie Jeziory-Osieck.
The nature reserve was set up by ordinance of the Minister of Environmental Protection, Natural Resources and Forestry (MP No. 2, item 415 of 1996) on the area of 62.37 ha. It is located in the municipality of Sobienie-Jeziory. It is a partial forest reserve. The aim of the reserve is to protect the mixed deciduous stands, coniferous and mixed stands with a considerable degree of naturalness and several species of birds. The flora includes protected species, such as mezereon and common ivy, partially protected, such as black currant, guelder rose, buckthorn, marsh Labrador tea and lily of the valley. The rare species include dog's mercury, barberry and kidney wort. The reserve is home for small numbers of birds such as the honey buzzard, sparrowhawk, green sandpiper, stock dove, middle spotted woodpecker, bullfinch and woodcock.