As marine environments within the adventure domain are future key-settings for recreational SCUBA diving experience, SCUBA-based textual materials should provide insight into environmental knowledge that is well connected to the novice divers' behaviour and attitude. This research is concerned with a major recreational SCUBA diver manual for novice divers from a position that seeks to explore its focus and scope of environmental knowledge in semantic networks. However, results obtained from thematic analyses of environmental knowledge emerged two sub-themes: marine-based conservation and aquatic life. Analyses of textual data indicated that the manual has groundling statements and notes on environmental knowledge. Furthermore, analyzing manual' environmental documents showed that there is no skill-related knowledge, which attributes to SCUBA divers' environmental behaviour and attitude towards underwater environment.