To investigate the sediments deposited in the lake that was flooded due to Holocene sea level rise, two cores were sampled. Length of the cores is 459 cm (M1-A) and 407 cm (M2). Semi-quantitative geochemistry of the cores was determined by XRF core scanner in 1 cm resolution for both cores and 2 mm resolution, in the interval from 114-242 cm, for M1-A core. Additionally, total organic carbon and nitrogen were analyzed in 1 cm resolution in M1-A core in interval from 114-237 cm, while δ13C was determined in 10 cm resolution from 5 - 459 cm. Furthermore, semi-quantitative X-ray diffraction was done in 3 cm interval from 114-239 cm in M1-A core. Research was done on the eastern Adriatic coast on the Island of Mljet, Croatia, in marine lake Veliko jezero. Veliko Jezero is a submerged doline.