In order to describe relations between tourism and landscape, it is important to operate within two scopes. The first is landscape potential and the second – the way it is used by tourists. In the paper, the problem of dynamic and diversity of tourist nature-based activities was addressed. Although the problem is of primary character, it remains poorly recognized due to difficulties in data collection. This concerns especially local scale studies within areas where it is difficult to use automatic monitoring. Despite abundance of methods of remote acquisition of data on tourism traffic, field measurements still have some advantages. What is important, they allow to combine quantitative and qualitative observations, making their interpretation more fruitful. The method of on route measurements described in the paper was implemented to assess the level and diversity of tourist flow in the Great Masurian Lakes. Tourist activities (divided in several categories) were being identified every 30 minutes during 12 days long sailing cruise. At the same time, qualitative observations were conducted. The proposed method proved to obtain rich data in economically efficient and relatively easy way. Some of the initial results have been presented to prove this statement.