The Blue-Cloud thematic Virtual Labs (VLabs) are the main test beds for users to get the hang of the Blue-Cloud framework, exploiting the 10+ million datasets available via the Data Discovery and Access Service (DD&AS), as well as the easy access to the collaborative VLabs via D4Science and the EOSC federated login. These collaborative workspaces hosted in the Blue-Cloud Virtual Research Environment (VRE) are serving more than 1,300 users in total spread across more than 20 countries. Five Virtual Labs were developed and deployed in the Blue-Cloud pilot project, making use of the analytical tools and generic services as provided through the VRE, and the data repositories, as made accessible via the DD&AS and through external data services...