The mines that will be used as test sites during the project lifetime are (in temporal and difficulty order):
- Kaatiala Mine, Finland (June 2018)
- Idrija Mine, Slovenia (September 2018)
- Urgeiriça Mine, Portugal (early-2019)
- Ecton Mine, UK (mid-2019)
Ecton Mine, that will represent the last test site for UX-1, will result in a resurveying of the flooded mine floors that nobody has seen for more than 160 years and that will bring important geological information as well as documentation from important mining heritage lost for a long time.