This article explains how the project-based lab (PJB-Lab) trains critical thinking skills, creative thinking skills, communication skills and collaboration skills (4C Skills) and produces two project products from the application of the fluid concept, namely the application of Archimedes' law on submarine projects and the application of hydrostatic pressure on the project's hydraulic pumps (Hydram). This study uses a quasi-experimental method involving 112 students studying at two universities located in the province of Aceh, Indonesia. The results of the study show that 4C skills can be improved well with an increase in the high category. Therefore, PJB-Lab has been proven to be effective in facilitating and training the 4C skills of prospective physics teachers at universities and can be considered for application with students in schools.