In the context of the critical sustainability problem of marine plastic pollution, the present paper presents a quasiexperimental research that explores the effects that participating on beach clean-up has on students’ knowledge,awareness and behavioural intentions. Considering this intervention as an outside of school practical implementation of Education for Sustainable Development (ESD), this research aims to determine if the addition of direct experiences with nature within ESD programs can lead to a behavioural change in favour of the environment. Analysing the factors that influence pro-environmental behaviour and the role that ESD has on transforming society towards a more sustainable one, a one-time pre-test post-test research with non-equivalent groups was performed. A questionnaire on beach litter and self-reported behaviour, implemented in two schools of the Amalfi Coast, Italy, indicate that in comparison to a group which only received a lecture, a group that participated in a beach clean-up increased their knowledge and awareness towards marine plastic pollution, in addition to their willingness to participate in another beach clean-up. This supports the theory that learning in nature can have a higher influence in shaping pro-environmental behaviour, and therefore the inclusion of this type of activities within ESD programs can help beat marine plastic pollution.