This paper reports the site investigations (geological, geophysical and geotechnical), mass and material properties of weak travertines, and their reinforcement for the Antalya Aquarium complex. Weak travertines have poor engineering properties, such as high deformability and insufficient strength. This causes problems in the construction of engineering structures. In this case, detailed investigations were required to determine the potential risk to the foundations for the Aquarium and facilities, and to determine the measures required to mitigate against risk of failure. The mass and material properties of the weak travertines and overall reinforcement of the rock foundation were investigated, and further measures for the aquarium foundations were recommended and implemented.