Finland is a highly coastal country with a large archipelago area and numerous lakes. Consequently, these provide an essential environment for water-based outdoor recreation activities. To improve the information base for evaluating the welfare effects of policy instruments addressing water quality, such as the EU Water Framework Directive, this study examined the effects of changes in water quality on the recreation benefits, focusing on swimming trips in Finland. National recreation inventory data were used to provide information on welfare changes at the national level. The combined travel cost and contingent behavior approach revealed that the recreation value of a swimming trip in the current state was approximately 16 euros. The approach allowed assessment of the welfare effects of water quality changes beyond the observed levels, showing that a hypothetical decrease in water quality to a level at which the water visibility would be less than 1 m and abundant slime would exist decreased the value to 9 euros. Water quality improvement to a level at which the perceived water visibility would be over 2 m and no slime would exist increased the value per trip to 22 euros. In total, the overall annual value of all visits made for swimming in the case of water quality improvement increased the recreation benefits by 53–80%, while a deterioration in quality decreased the benefits by approximately 80%.

芬兰是一个高度沿海的国家，拥有大群岛地区和众多湖泊。因此，这些为水基户外休闲活动提供了必要的环境。为了改善评估诸如欧盟水框架指令之类的针对水质的政策工具的福利影响的信息基础，本研究研究了水质变化对娱乐利益的影响，重点是芬兰的游泳旅行。国家娱乐清单数据被用来提供有关国家一级福利变化的信息。结合旅行成本和偶然行为方法，发现当前状态的游泳旅行的娱乐价值约为16欧元。这种方法可以评估超出观察水平的水质变化的福利影响，结果表明，假设水质下降至水能见度小于1 m且存在大量煤泥的水平，则价值下降至9欧元。将水质提高到感知的水能见度将超过2 m的水平，并且不会产生煤泥，使每次旅行的价值增加到22欧元。总体而言，在改善水质的情况下，所有游​​泳访视的年度总价值将娱乐收益提高了53–80％，而质量下降则将收益降低了约80％。将水质提高到感知的水能见度将超过2 m的水平，并且不会产生煤泥，使每次旅行的价值增加到22欧元。总体而言，在改善水质的情况下，所有游​​泳访视的年度总价值将娱乐收益提高了53–80％，而质量下降则将收益降低了约80％。将水质提高到感知的水能见度将超过2 m的水平，并且不会产生煤泥，使每次旅行的价值增加到22欧元。总体而言，在改善水质的情况下，所有游​​泳访视的年度总价值将娱乐收益提高了53–80％，而质量下降则将收益降低了约80％。