COVID-19 and subsequent government health containment measures have slowed down economic activities worldwide, particularly tourism. With the number of foreign tourists entering Thailand during 2020 and 2021 greatly diminished, the number of tourists at marine and coastal attractions in Southern Thailand has declined as well. This study found evidence of a relationship between the decline of the number of tourists and marine resource recovery. This recovery appears in the form of cleaner beaches, clearer seawater and increased sighting of marine animals. Between 2020 and 2021, official reports found increased sighting of dugongs, dolphins, blacktip reef sharks, whale sharks, leopard sharks, sea turtles, green turtles, hawksbill turtles, and false killer whales at marine national parks in Southern Thailand. The study also found that, prior to the COVD-19 outbreak, the number of tourists at Patong Beach and Maya Bay exceeded their tourism carrying capacities. Finally, this study proposes eight policy measures related to tourism management for marine resource sustainability: conservation and recreation zoning, enforcing marine park closure, redesigning marine park entrance fee systems, ensuring adequate recreational facilities, stricter enforcement of the law, promoting alternative tourism sites, encouraging more inclusivity and participation in decision making processes, and enhancing public awareness.