Growing environmental concerns and increasing public expectations for corporate environmental responsibility have made sustainability communication an important component of organizational communication. Although social media enables companies to communicate sustainability initiatives, the selective presentation of environmental information and insufficiently substantiated claims may create potential for greenwashing. This study aims to analyze the forms of green communication and identify potential greenwashing characteristics in the sustainability communication of the @aqualestari Instagram account from January to December 2025. Using a qualitative approach, the study analyzed 84 Instagram posts through qualitative content analysis. The analysis identified sustainability communication themes and examined potential greenwashing characteristics using the Seven Sins of Greenwashing framework. Legitimacy Theory informed the interpretation of how environmental responsibility was represented in the account’s communication. The findings revealed six sustainability communication themes: religion, nationalism, and celebrations; community empowerment and collaboration; environmental education; natural resource and water conservation; waste management and the circular economy; and health and hydration. Three potential greenwashing characteristics were identified: hidden trade-off, vagueness, and no proof, with hidden trade-off emerging as the most prominent. This characteristic was reflected in the emphasis on water conservation, plastic waste management, and circular economy initiatives, while other environmental issues associated with plastic packaging, resource consumption, and business operations received comparatively less attention. The findings suggest that sustainability communication may reinforce an organization’s environmentally responsible image while presenting a less comprehensive account of its environmental responsibilities. This study highlights the importance of balanced environmental disclosure, specific and measurable claims, and verifiable supporting information to strengthen the transparency and accountability of corporate sustainability communication.