Transnational Access (TA) or Remote Access (RA) will be provided to selected ‘user groups’. User groups are teams of one or more researchers (users) led by a ‘user group leader’, also understood as principal investigator (PI) or chief scientist. A user group eligible for Transnational Access (TA) must meet the following strict criteria:

1. Affiliation/Country of work: The user group leader (PI) and the majority of the users must work in a country other than the country(ies) where the installation is located (unless access is provided by an international organisation, the Joint Research Centre (JRC), an ERIC or similar legal entity).
2. International collaboration: Single applicants are now eligible to apply. User groups with more than four users from different organisations must include partners from at least two different countries (current affiliation).
3. Dissemination: Only user groups that are allowed to disseminate the results and knowledge they have generated in the context of the access may benefit from the TA, unless they are working for small- and medium-sized enterprises (SMEs).
4. Expertise: The user group leader (and designated chief scientist, if applicable) must have the appropriate scientific/ technical expertise to conduct proposed work.
5. Complete information: All information required for the scientific and logistical evaluation of the AQUARIUS eligibility criteria and the application must be entered into the AQUARIUS online application platform. This is, for example, the research infrastructures applied for or the number of user group members who want to access an AQUARIUS research infrastructure, contributions to the call challenges or scientific publications.
6. Data Policy: The user groups must agree to comply with the AQUARIUS data policy.

Applications with clearly defined contributions to the EU Mission Ocean and Waters, the inclusion of citizen science and applications from early career researchers are strongly encouraged and supported by AQUARIUS