Regular Members of the Network may be local and regional authorities operating in the countries belonging to the Three Seas Initiative, those are Austria, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovak Republic and Slovenia.
Entities representing business institutions, universities, etc. may become Associated Partners of the Network.
Entities operating in other countries than those belonging to the Three Seas Initiative, especially those bordering such countries, may become Associated Partners of the Network.