Levees, as earthen structures, are particularly prone to damage during seismic events. Seismic loading can result in global levee instability, however failure mechanisms are also associated with large deformations due to soil liquefaction within and below the levee. To evaluate the liquefaction potential below the levees, and for the purposes of liquefaction mitigation design, it is necessary to carry out detailed in-situ and/or laboratory investigation works. This is challenging mainly due to the large lengths of the levees, and considering the limited financial and time resources for the implementation of investigation works. The paper gives an insight into several examples of investigation works carried out to identify the liquefaction potential, with an overview of the designed measures for the rehabilitation of the underlying soil. Examples include Puscine levee in Međimurje County, which was reconstructed due to the unsatisfactory height from the aspect of high water, and the Hrastelnica levee in Sisak-Moslavina County, which was damaged in earthquake of December 2020. While a large number of SPT tests were applied along the Puscine levee to assess the liquefaction potential, various geophysical and geotechnical methods were used at the Hrastelnica levee. As part of the LeveeLiq research project, additional investigations were carried out on the latter levee using a multi-sensor approach with the aim of developing a methodology for mapping the spatial variability of the liquefaction potential under the levees, which will be presented in the paper.