The Divers Alert Network Europe has developed 10 guidelines to help divers and diving centers to implement preventive measures against the SARS-CoV-2 virus and to minimize risks as much as possible. The document should be updated as new knowledge is obtained.
Update 22.5.2020: The Global Underwater Explorer (GUE) has also published guidelines.
Update 2.6.2020: Green Fins has provided some information, including additional guidelines on disinfection, environmental considerations, and a manual for diving centers that want to review and improve their sustainability measures. The manual can be read online for free and usually costs £20.