The article is an attempt of a synthetic presentation of water obstacles influence on forces actions. The characteristics of a water obstacle defining its tactical features have been presented. Numerous difficulties and divergencies result from mere stating precisely which of the water obstacle characteristics has an essential impact on forces’ actions. Taking into account the degree of difficulties appearing in case of overcoming a water obstacle, their division criteria have been described. As it results from introductory evaluations, the character of river banks, their slant and the time to cover the water surface connected with the river width and current speed have a great importance. Such a big impact of water obstacles on forces actions results primarily from difficulties to come across even in case when, theoretically a given combat equipment has got sailing (floating) abilities. From the conducted considerations results that the effectiveness of carried out combat actions in water obstacles area will depend on many factors, the most important of which are the following: the degree of armed forces preparation to conduct actions and the ability to take advantage of the terrain features.